Runs good for 20 minutes, then dies and won't start until the next day

I am sick of my truck leaving me stranded.

It is a 1991 C1500 2wd, ext cab, short bed 5.7L engine with about 300k miles on it that I have had for a year. Supposedly a different 350 engine and transmission was put in a couple years ago.

This problem has been going on for 2 weeks. I'll start the car up and it runs just fine, no problems. After driving for about 20 minutes, the engine will die while driving, and will not start back up until the next day. I have sat in the car for literally 4 hours patiently waiting for it to start. I'll turn the key and the engine will rotate, but will not start. When someone shows up to give me a jump after the battery gets low, it will not start. I'll go home and go to sleep, and sometime the next day I'll go to my truck, and it will start back up, and I'll drive back home, and I'll make it as long as it takes less than 20 minutes.

It is not just a "morning problem", but a "first time I have started the truck that day" kind of problem. Last week, it happened to me in the mornings. On Saturday, I didn't leave my house until 2pm and the problem happened. Today, I first drove it at 8pm, and the problem happened.

Things I have changed so far (mostly from Autozone):

Starter - burnt it out when it first died 2 weeks ago, now I know not to crank when below 9 volts - lifetime warranty

Spark plugs - no more engine popping or driving with 2 feet - changed last week on Tuesday - AC Delco CR43TS gapped at .035

plug wires - changed all in November, since I noticed one of the old ones was tore - lifetime warranty

Distributor cap and rotor - changed last month when the engine started popping - autozone

Ignition control module- I changed today, I really thought that would fix the problem after speaking with the Autozone guy - lifetime warranty

Ignition Coil - changed last month because of popping

Fuel Filter - changed last Thursday, thinking it was a fuel problem



Here are some of the other symptoms I have been noticing over the last couple months:

Pretty bad gas mileage, I know it is a V8, but it is just as thirsty when I am not carrying anything as when I am pulling a car

A couple months ago, after driving for about 30 minutes or so, the engine would make a "Pfft" noise and would start popping and I would have to drive with 2 feet to keep the engine running.

Did you do any testing, when the vehicle refused to start? Yes, if your by yourself, not much you can do. If it cranks good but, won't start, have a helper crank it, while you visually check for spark at the plugs. If spark everywhere, use a gage and check fuel pressure. Any applicable trouble codes? Can you visually see injector spray pattern, TBI, engine cranking? If you see a spray pattern, that doesn't mean the pressure is good.

The popping noise, might be a timing issue?

Today I started the car and let it run in front of my house. I gave it a little gas while it was running and it died after 15 minutes.

I pulled off the spark plug wire closest to the front of the car on the drivers side. I layed the wire on top of the valve cover with a small screwdriver stuck in it. I had a friend try to start the truck and I saw a spark from the screwdriver to the intake.

I came back here to post this update, then I re-read your reply and noticed you suggested I check for spark EVERYWHERE, and I only checked one plug wire.

I guess I'll have to check the other 7 in the morning since it is already dark outside.

I don't know how to check fuel pressure or for trouble codes, but I'll do a search for instructions.

Take off the air cleaner and have a friend try to start it and see if the injectors are spraying fuel.

A few months ago, I have an ignition module go bad on my 90 K1500. Even though the ignition module was bad, the injectors were spraying fuel.

There is no service port on the TBI fuel lines so you need a special tool to check the fuel pressure.

//2000CAYukon

Ok, I'll check the injectors in the morning.

I took off the ingnition control module yesterday, thinking it was the cause of my problem. I took it to Autozone tested it, and it failed every test, I think there were 7 or 8 tests in all.

I bought the new one for $42 and put it on last night, but the truck still died on me after 20 minutes of driving - the exact same problem, so replacing the control module didn't fix it.

The autostores sells a TBI fuel pressure gage, you just tee into the supply line. Sometimes it is easier for me to tee in at the fuel filter. Years ago, when my oldest boy got his first car, it was tbi, I made a fuel pressure gage to tee into his system. It worked fine, still have it. To check for codes, you place jumper wire between A & B terminals of datalink connector. Turn the key just till the dash lites come on, no further. The mil starts flashing, you count the flashes to get the codes. Your looking for two digit codes.

To check for codes, you place jumper wire between A & B terminals of datalink connector. Turn the key just till the dash lites come on, no further. The mil starts flashing, you count the flashes to get the codes. Your looking for two digit codes.


It gave me a code 12 - so I guess no problems there.

have you tryed putting a new picup coil in dist? or maybe your cat's pluged?

When it died, I cranked the engine and the injectors were still squirting fuel just like before. I don't have a pressure gauge, but it seems like the pump is working.

I checked the wires on the drivers side when it died and they all sparked but I still need to check the passenger side.

Funny thing is it is taking less time to start up after it dies, maybe weather related since it is 70 degrees today and it has been in the 30-40 degree range for the last few months.

I am starting to think the problem might not be a lack of fuel or lack of spark but maybe too much fuel- meaning the engine is getting flooded. Is that a possibility?

The passenger's side wires have spark too. I did notice that the passenger side valve cover has an opening in it where something obviously is supposed to be sticking in there. Would that be for the pcv valve? Could that be related to the engine dying on me?

The Engine Coolant Temp Sensor (located in the intake manifold near the tstat) tells the ECM what temp the engine is so that the ECM can control the amount of fuel to the engine.

With the engine warm, it should read around 100 ohms. If it is telling the ECM that your engine is cold but it is really warm, it can cause it to run poorly.

Usually, if the ECT sensor was bad, the truck would restart after the engine cooled down.

I wonder if the cat is plugged. You should remove the 02 sensor from the exhaust manifold and try to start it.

You may have some kind of heat soak issue. Is the spark a good blue spark?

//2000CAYukon

have you tryed putting a new picup coil in dist? or maybe your cat's pluged?

No, I haven't tried the pickup coil

The Engine Coolant Temp Sensor (located in the intake manifold near the tstat) tells the ECM what temp the engine is so that the ECM can control the amount of fuel to the engine.

With the engine warm, it should read around 100 ohms. If it is telling the ECM that your engine is cold but it is really warm, it can cause it to run poorly.

Usually, if the ECT sensor was bad, the truck would restart after the engine cooled down.

I wonder if the cat is plugged. You should remove the 02 sensor from the exhaust manifold and try to start it.

You may have some kind of heat soak issue. Is the spark a good blue spark?

//2000CAYukon


This is my first time doing this so I don't know what a good spark would look like, but I did expect the spark to be bigger.

Can I just unplug the 02 sensor or do I have to actually remove it?

If the cat is plugged, it will usually run if you remove the 02 sensor. Just unplugging won't help.

//2000CAYukon

Since it runs for 20 minutes, see what the spark looks like in the morning and compare to what it looks like when it does not run.

//2000CAYukon

Check the ECT sensor, EGR and IAC valves, and look for vacuum leaks.

i had a similar problem with my truck. im prety shure that your alternator is going out. you should take your alternator out and take it to autozone and have them check it. they do this for free.
your truck will run on the juice from your battery antil their isnt enough juice to fire your spark plugs in turn leaving you without enough juice to start your truck antil the battery has had enouph time to regain a little charge. this is why you have to wait till the next morning to start it again. and if you drive it to offten this way your battery will go bad on you as well.

...I did notice that the passenger side valve cover has an opening in it where something obviously is supposed to be sticking in there. Would that be for the pcv valve? Could that be related to the engine dying on me?

I would look into this as it could be a large vacuum leak if it is the PCV system. Do you have a picture you could get for us? It sounds like the PCV system to me.

I would look into this as it could be a large vacuum leak if it is the PCV system. Do you have a picture you could get for us? It sounds like the PCV system to me.


Here is the picture of the passenger side valve cover with the air cleaner removed. Do you know what goes in the hole? Could that be related to the engine dying on me?

Here is the picture of the passenger side valve cover with the air cleaner removed. Do you know what goes in the hole? Could that be related to the engine dying on me?


The guy at the auto parts store told me that was for the PCV valve, so I bought it and put it in, but the car still died after 20 minutes.


My tailpipes are kind of rusty, so I guess the next thing I will do is take the truck to the muffler shop to get chrome tailpipes extentions. I figure while I am there, I can have the guy check to see if the catalytic converter is clogged, like the other poster suggested I do.

Is there anything else I should try to do myself first?

That hole is for the PCV system on my 97 for sure, and I am pretty sure it is the same for yours.

Here is a picture, you are missing a vacuum hose off the bottom of your throttle body, and the PCV valve.

This is the best picture I could find. Thanks Google Images.

http://www.aeswave.com/Articles/ProductArticles/Flatrater/engine.jpg

Missing these parts would cause a HUGE vacuum leak at the base of the throttle body.

I'd just like to know where they could have went.

Never mind, I see in your picture that the PCV hose is there, its just you are missing a PCV valve and a 90 degree elbow. Either way it will cause a HUGE vacuum leak and needs to be fixed before we try and diagnose any further on this die/no start when warm issue.

Never mind, I see in your picture that the PCV hose is there, its just you are missing a PCV valve and a 90 degree elbow. Either way it will cause a HUGE vacuum leak and needs to be fixed before we try and diagnose any further on this die/no start when warm issue.

Yes, I went ahead and purchased a PCV valve and installed it. Unfortunately, I didn't notice any difference as the truck still died after 15 - 20 minutes.

I sat in the driver's seat today and noticed the temperature gauge was in the red even though the key was not in the ignition. In fact, I haven't even started it today. It did not overheat yesterday when I ran the truck after putting in the PCV valve.

jdmccright suggested my problem may be the coolant temperature sensor. I went ahead and purchased it since it was only $11. I think I will be changing it first before I try anything else, as soon as I can find a diagram to show me where to find it.

It is screwed into the intake manifold just to the left of the upper radiator hose water neck with a 2-wire connector.

The missing PCV would not cause a no-start. It would cause the truck to run rich...and make a messy valve cover.

It is screwed into the intake manifold just to the left of the upper radiator hose water neck with a 2-wire connector.

The missing PCV would not cause a no-start. It would cause the truck to run rich...and make a messy valve cover.


OK, just changed the coolant temperature sensor, started it up, and it still died after about 15 minutes. Any suggestions on what to try next?

I wonder if the cat is plugged. You should remove the 02 sensor from the exhaust manifold and try to start it.

//2000CAYukon


I think I narrowed down the problem. I removed the oxygen sensor as you suggested and it ran for over 20 minutes without dying.

Of course, error code 13 popped up since I had the oxygen sensor unplugged, but that was expected.

I put my hand near the tailpipe and felt warm air blowing on it, so does that mean the converters are not clogged?

I already bought the O.E. Bosch 02 sensor from Autozone for $20, but the engine is too hot right now to put the new one in, so that'll have to wait until the morning.

Is the PCV hoses connected to the front of the TBI unit? Hard to tell from the picture.

The cat could be clogged or you are having an issue running in closed loop.

//2000CAYukon

Is the PCV hoses connected to the front of the TBI unit? Hard to tell from the picture.

The cat could be clogged or you are having an issue running in closed loop.

//2000CAYukon


Yes the PCV hose is connected to the TBI. There is a plastic tube with hoses on both ends of it. One of the hoses is 90 degree angle hose going from the plastic tube to the bottom front of the TBI, and the other straight hose is going from the other end of the plastic tube to the PCV valve.

With the o2 sensor unplugged from the electrical connector and unscrewed from the exhaust manifold, the truck ran over 20 minutes without dying.

Today I installed the new o2 sensor in the manifold and plugged it into the electrical connector and started it. The truck died again after running for 20 minutes.


When the truck dies, I know that the injectors are still squirting gas, and I still have spark at each wire. Remember that I have no check engine codes on the dash, except of course when I unplugged the o2 sensor. I believe that my problem is either a clogged catalytic converter or I suspect that the computer is incorrectly adjusting things which makes the truck die when it goes to closed loop.


My new plan is to keep the sensor installed in the manifold, but unplugged from the electrical connector. I believe that if it will run like that, without dying on me after 20 minutes, that would indicate that my catalytic converter is not clogged up.

Then, I will at least know if the problem is exhaust related or if it is something else.

Any other suggestions?

if the cat converter is bad as it heats up with exhaust gases it may be collapsing...if it does get hot and then closes totally with no exhaust you cannot get the engine to run it will stop...

with the engine running plug up the tail pipe with a rag to see if this is how your issue compares

the engine is a pump no discharge no sucking ..

With the o2 sensor unplugged from the electrical connector and unscrewed from the exhaust manifold, the truck ran over 20 minutes without dying.

Today I installed the new o2 sensor in the manifold and plugged it into the electrical connector and started it. The truck died again after running for 20 minutes.


When the truck dies, I know that the injectors are still squirting gas, and I still have spark at each wire. Remember that I have no check engine codes on the dash, except of course when I unplugged the o2 sensor. I believe that my problem is either a clogged catalytic converter or I suspect that the computer is incorrectly adjusting things which makes the truck die when it goes to closed loop.


My new plan is to keep the sensor installed in the manifold, but unplugged from the electrical connector. I believe that if it will run like that, without dying on me after 20 minutes, that would indicate that my catalytic converter is not clogged up.

Then, I will at least know if the problem is exhaust related or if it is something else.

Any other suggestions?


OK, it died again with the o2 sensor still installed but unhooked from the electrical connector. I guess that means that my problem is the catalytic converter is clogged up.

OK, it died again with the o2 sensor still installed but unhooked from the electrical connector. I guess that means that my problem is the catalytic converter is clogged up.

normally a restricted cat converter gradually gets restricted , and MPG/POWER is gradually lost ....

when sudden damage like this occurs something caused the converter to melt in most cases ..

could be the muffler

normally a restricted cat converter gradually gets restricted , and MPG/POWER is gradually lost ....

when sudden damage like this occurs something caused the converter to melt in most cases ..

could be the muffler


Ok thanks. I guess I'll be changing the muffler at the same time the converter is replaced.

I have an 89 blazer and I have the exact same issue... I have done everything to try and fix the problem... Literally everything that you have discussed I have already done. Only difference is we took out our cat. converter and have brand new mufflers on it! Unfortunately that's where your discussion stops... I'm hoping we can continue the discussion and you may be able to help me with this issue! We were thinking it could possibly be a grounding issue but haven't checked it out yet? Please help!

The passenger's side wires have spark too. I did notice that the passenger side valve cover has an opening in it where something obviously is supposed to be sticking in there. Would that be for the pcv valve? Could that be related to the engine dying on me?

PCV VALVE:grinyes:
That could be your problem.
Get the PCV valve all hooked back up and working right.

I have an 89 blazer and I have the exact same issue... I have done everything to try and fix the problem... Literally everything that you have discussed I have already done. Only difference is we took out our cat. converter and have brand new mufflers on it! Unfortunately that's where your discussion stops... I'm hoping we can continue the discussion and you may be able to help me with this issue! We were thinking it could possibly be a grounding issue but haven't checked it out yet? Please help!

How about starting your own post with your vehicle details... like what engine / fuel supply / mileage and other details like engine temp and oil pressures.

I doubt you have a 1989 blazer with this 350 CU engine !

Gee thaksn for the help! Just so you know I have an 89 Chevy full size blazer with a 350 with TBI... Start great no matter what time of day it is runs OK for about 20 minutes then dies out... Won't start again till next day. Did all the same things you discussed no change... But I will have you know... I just figured it out without your help and I'm a chick! So good luck hope you can figure it out too... Or maybe I should come show you what's up!

Let me give you some advice . get rid of that gas guzzler . what do you get 10 MPG. Not running , this vehicle is doing you a favor by saving some cash.

with a vehicle this old it could be anything. especially when its been changed from OEM design.

Oh... I got it running and it runs great! With the 6 inches of suspension lift, 3 inches of body lift, the 35s I got on it, and the dual 3 in exhaust... Its more like 9mpg. Not to mention the 8gauge steel I used to replace the floor, the self made steel back bumper and front bumper with bull bar, and the self made steel roll bar! Nothin but fun... Mud, sand, two tracks... Bring em on! And if you think this ones a gas hog... You should see my denali with 11 inches of lift, 44s, custom candy paint job, and cutom upholstered ostrich leather and suade interior! Yeah! :grinyes::grinyes:

Glad you got her going! If you know what you did to fix the problem, please post it so everyone can benefit.

I personally love the old TBIs, they are so much simpler than the next gen MPFI units and nearly bulletproof. They usually just need a good cleaning once in a while, especially the IAC.

A girl that likes big trucks and can weld? I think I'm in love....

Glad you got her going! If you know what you did to fix the problem, please post it so everyone can benefit.

I personally love the old TBIs, ty are so much simpler than the next gen MPFI units and nearly bulletproof. They usually just need a good cleaning once in a while, especially the IAC.

A girl that likes big trucks and can weld? I think I'm in love....

Lol! Well after changing or testing just about everything it came down to the coolant temp sensor... When its bad it madue the ICM think that the engine is really cold and the injectors just poor the gas into the motor... Not only the sensor itsself but the wire and connector as well. I had the air filter off so i could see the tbi and watch it spray gas... I knew right away it was way too much... If i gased it it would pop spit and sputter and backfire. After 15-20 min it wad flooding itsself out And the reason it wouldnt restart. As soon as I unplugged the coolant temp sensor the engine smoothed out and the fuel was coming out in a steady stream rather then spraying out. I shut it off several times and restarted it everytime! If this works make sure you check your plugs that they're not burned due to exsesive gas... Check oil make sure its not full of gas and it wouldn't hurt to use some fuel stabalizer and injector cleaner! Hope this works for you! :wink:

"Check the ECT sensor, EGR and IAC valves, and look for vacuum leaks."

Who said that? 3 years ago? Oh yeah, I did.

"Check [B]the ECT sensor[B], EGR and IAC valves, and look for vacuum leaks."

Who said that? 3 years ago? Oh yeah, I did.

I seen that... But nothing about the coolant temp sensor. i seen it mentioned in one of these but nothing about it being the problem. Both my coolant temp sensor and its wires and conector were bad. It made the vehicle think it was like -40° causing the injectors to spray too much gas and eventually flood its self out. As i was watching the injectors spraying gas into the motor i unplugged the coolant temp sensor and it went from a spray to a steady drip stream and smoothed right out! I let it run for a half an hour and no problems. I throttled it up no spitting sputtering popping or backfiring. I shut it off and bam it started right back up. It was hard to believe that was the problem but there was nothing left to change...! If I knew what your codes are i might be able to help more... But this is what fixed my problem. Also remember it is possible to getnew parts that are bad... And most people change the part but forget to check the wires and connectors. :smile:

Did whoaskew fix his problem? I am having a very similar problem on my Suburban, I changed out the intake manifold gasket about two weeks ago and she has been running like a top. I did a full tune up, wires plugs rotor cap button fuel filter etc. Today my wife calls me and she had driven like WHOASKEW for about twenty minutes and it suddenly died on her. I had it towed home and the fella drove it off the truck, she was like what the heck, fella said to her yeah, I drove it on the roll back. When I got home from work i looked over all of my work and the only obvious thing i found was the battery ground was loose so I replaced the terminals and then checked the battery and alternator battery read 12.9 a weee bit low but acceptable. the alt was putting out at 14.4 so that was good. It has fire and fuel. i drove it for about 20 and then I felt a small jolt and just like that it was dead. no hesitations no jerking no power loss etc. It wouldnt start back up. Would turn over kinda slow almost thought it ws gonna hydrolock because of how hard it was for the starter to turn the motor. I tried a couple more times over the next half hour waiting on my wife to come fetch me. I towed it home with the Jeep. Got home tried and nothing. looked over it checked spark it was there but not strong kinda orange not blue. Sprayed a little bit of fluid in the tb and she fired up ran rough and shut down I then thought it was the fuel, ten minutes later after a buddy came over he reached in and i will be dern it fired up no problem. So I am not the type to throw money at a problem, i am suspecting the coil is having a thermal break down, or the icm is failing. exhaust seems strong fuel pump is humming as it should. I am also thinking that I may have the timing advanced a tooth maybe. Any suggestions?

Check the engine coolant temperature (ECT) sensor. If it isn't reading correctly, the ECM will think the engine is cold when it is hot.

Thanks for taking the time to post your responses and I hope that this is the answer to my problem as well, I have a 1991 Chevrolet c/k 1500 4wd and so far I've only changed the distributor cap and rotor button also bought spark plugs and wires and coil pack just for tune up purposes, hope you're previous posts saves me time and money...

Really glad I found this thread! I have a 1978 Ford Grumann E350 V8 5.8. It's having all the same issues as above. Starts great cold then stalls after about 20 min. I replaced the ignition switch, ignition module, ignition coil, new plugs, solenoid, battery, alternator, starter, voltage regulator, rewired a new line to the coil with new ballast resistor and new start line from the solenoid to the coil. Was getting ready to dive into the distributor tomorrow when I found this thread. I think I will try and locate the coolant temp sensor first and try that. Any other ideas? This is a food truck and I need it making money! Thanks for the info already givin. It's always helpful to know your not alone in your frustration!

Really glad I found this thread! I have a 1978 Ford Grumann E350 V8 5.8. It's having all the same issues as above. Starts great cold then stalls after about 20 min. I replaced the ignition switch, ignition module, ignition coil, new plugs, solenoid, battery, alternator, starter, voltage regulator, rewired a new line to the coil with new ballast resistor and new start line from the solenoid to the coil. Was getting ready to dive into the distributor tomorrow when I found this thread. I think I will try and locate the coolant temp sensor first and try that. Any other ideas? This is a food truck and I need it making money! Thanks for the info already givin. It's always helpful to know your not alone in your frustration!

This tread is old and worn out and for a different truck.
Best to start a new thread for tout problem.
You may have a fuel problem on yours truck.
I thing I would do is to check fuel pressure when it quits.

Seems to be the electronic pick up assembly. The magnet is overheating I think. The casing around it is cracked. On my way to get a new assembly right now.

That was it! The pick up coil in the distributor was bad.

That was it! The pick up coil in the distributor was bad.

that's good you fixed it. now you should post this in the FORD section that way it may help someone that is still running one of these..

pickup coils were a common failure in the old days.

"Check the ECT sensor, EGR and IAC valves, and look for vacuum leaks."

Who said that? 3 years ago? Oh yeah, I did.
I seen that... But nothing about the coolant temp sensor.
ECT sensor = Engine Coolant Temperature sensor.

To all who are or was having these problems. I have a 2002 Tahoe that would run for twenty minutes or so and die as if it were running out of gas. I could crank it if left to sit for awhile, but then it would always die. It would idle fine during this time, but if I accelerated, it would bog down and choke. I had it towed to a reputable mechanic who could not figure out what the issue was, because when it was running, it would not throw codes in reference to the fuel system and it showed good pressure readings. After a couple months of investigation and trouble shooting, I discovered that the fuel pump (that was not even a year old) was overheating. I changed the fuel pump and the problem was immediately solved. Hope this helps.

To all who are or was having these problems. I have a 2002 Tahoe that would run for twenty minutes or so and die as if it were running out of gas. I could crank it if left to sit for awhile, but then it would always die. It would idle fine during this time, but if I accelerated, it would bog down and choke. I had it towed to a reputable mechanic who could not figure out what the issue was, because when it was running, it would not throw codes in reference to the fuel system and it showed good pressure readings. After a couple months of investigation and trouble shooting, I discovered that the fuel pump (that was not even a year old) was overheating. I changed the fuel pump and the problem was immediately solved. Hope this helps.

I would find another repair shop with techs that know what there doing. the PCM/ECM/computer does not throw any fuel delivery type codes. SO what that means is if your engine dies like ON these vehicles , then the fuel system is suspect. on the fuel pump failures with these ... Never run the fuel below 1/4 or the fuel pump will die an early death. next never use an airtex fuel pump even if its free.. not worth the trouble of a breakdown. a simple quick fuel pressure reading reveals these issues quickly.. sometimes you have to drive the vehicle to see if it starts to loose pressures. 52-62PSI...

Thanks for the feedback. It is an unfortunate fact that the failed pump was a Bosch and the tank did go below 1/4 a few times. Fuel pressure tested at 61 psi. Sad to say, I really do think the mechanic didn't want to tackle the job.

Thanks for the feedback. It is an unfortunate fact that the failed pump was a Bosch and the tank did go below 1/4 a few times. Fuel pressure tested at 61 psi. Sad to say, I really do think the mechanic didn't want to tackle the job.

The bosch pumps have had some bad reports. airtex is the worst. 3-12 months.
2002 I believe still has a fuel filter that is replaceable . if so replace this every 30K miles. reduces pump failures.
replacing the pump is not easy time consuming. I do it with moving the bed back on a pick up. with the tahoe/suburban this is more of a problem esp if you have lots of fuel.tank drop.
ac delco and the delphi have had the best results.

Most of you forget about the air intake control which is trodle position sensor and the trodle plate. Just clean the plate and make sure the sensor is plug and functioning properly and put a new air filter all you need is air fuel and spark, you know that you have fuel and spark just focus on your air intake and exhaust the engine could flood if you don't have proper air intake

Do you know if your ignition module has a heat sinc or does it
Have heat sinc paste between where it bolts on . My 1995 firebird with a 350 LT1 was doing that. It would run fine for 15 minuites an quit. I would let it
Sit and come back about five hours later and it would start up and run for
15 min and quit again . My coil has a bracket with a heat sinc mounted too it the ignition module is attached to the heat sinc . I removed the hole unit and cleaned it . The heat sinc has a white heat sinc paste between it an the ignition module. I went to store (the source) an bought some paste for
15 bucks cleaned everything and reapplied the paste. There is a small air gap between the module an heat sinc the paste fills that void and allows goodnheat transfer . I am not sure if that was the problem but it started up and has not done it since the ignition module was over heating