Help..3800 Running Rough

Please help. I'm at my wits ends. I've got a 1990 pontiac bonneville with the 3800. the car is barely running. here's the deal. for about a month, it would intermittently miss while driving down the road. then one day it went. car was running so rough i didn't know if i was going to make it home. it seems that if you keep it light on the throttle it almost runs fine. i'd say that you can give the gas peddle about 10 percent of it's travel. if you go past that it will start to spit, sputter, pop and cut out. Here's what i've done so far.
NEW PLUGS/PLUG WIRES
NES GAS FILTER
NEW AIR FILTER
NEW O2 SENSOR
NEW MAF SENSOR
REPLACED THE CAT
CHECKED FULE PRESSURE AT RAIL = 45PSI
CHECKED COILS, #3 WAS BAD AND REPLACED IT
RAN ALCOHOL AND FULE INJECTOR THROUGH TANK
RAN 2 TANKS OF 93 OCTANE, I USUALLY PUT THE 82 AND IT RUNS FINE.
CLEANED EGR VALVE OF CARBON DEPOSITS
CHECKED FOR VACCUM LEAKS
CHECKED TPS...used ohm meter, movement was smooth

even at idle, it kinda runs a little rough, but if you get to going down the road, as long as you stay off the gas, it will drive like nothing is wrong but like i said, there's a thresh hold that if you cross, it will cut out.. once you get it up to speed, say 70.. it will maintain that speed just fine without cutting out, as long as you barely give it gas. all this leads me to think about the TPS but as i said before, i've checked it. I replaced the crank sensor about a year ago, it was an aftermarket one. Any help would be greatly appreciated. thanks.

A few comments....lacking a definite explanation...
...doesn't this light up the CEL?..
TPS is OK, no doubt..this device is mostly used for transients (rapid throttle changes), not really for steady state throttle.
I'd suspect exhaust invasion...leaky EGR valve, leaky gasket or most possibly burnt exhaust valve. IN fact...were it not for the weird access to spark plugs...I would go for a compression test, at least to confirm or clear the valve option.

This can also be related to poor spark quality--spark has more problem going through denser atmosphere, which happens when throttle is more depressed.....and then the only remaining item in the loop is the ignition module...But this should give a CEL

I don't know what a cel is. Uncle has a compression checker, i'll get it today and check it out. thanks for the help. It's not throwing any computer codes. For checking the coils, first did a ohm test, they were all the same, .56 ohms... then uncle came over to pull plugs one at a time, first we let the car warm up then started pulling plug wires from the coil one at a time, all were firing a bright blue and made a pretty loud pop sound while arking, except for #3, it was a yellow spark and not so loud, so i put on a new one. when i cleaned the egr valve, i didn't put a new gasket on it, just used the old one.

I don't know what a cel is.... It's not throwing any computer codes. ..
OK you did it anyway : CEL = Check ENgine Light

Dirty fuel injectors?:2cents:

i've run a bottle of that fuel injector cleaner in my tank... i've also head that these cleaners don't really work, any input on them. is there any way i can take the injectors out and clean them?????thanks..

THe probability that ALL injectors start blocking at same time is very remote....dirty injectors can limit MAXIMUM power, but not normal driving..at least, not on a sudden...
...there has been a case of broken exhaust valve stem...almost similar symptoms...but, needless to say, very rare....not a high probability, but just to know it happens.It still can be a fire problem..but to me it does sound like intake contamination by stray exhaust. Since you have recently removed the EGR valve, I'd make a temporary gasket to totally block the valve..at least to make sure none of the 3 valves blocks open and test. Stray exhaust can sep through damaged lower intake manifold gasket...at least there were exhaust passages through intake manifold with carbs...may be I'm wrong now..just tell me...
THe burnt valve syndrome is also exactly like that..had that once long time ago...
Keep us informed of any findings, jeff......all the time someone comes with something totally unexpected..and we all learn for the next time.

I had this exact condition on a 95 Bonneville after all the things you have done and a little more I found that the ground between the block and the H-Frame was lost. Not battery to engine but engine to chassis ground (H frame on the bottom of the car.) There is also a ground just below the coil pack I have heard of going bad. So... check the resistance between the engine block and the H Frame should be a few Ohms (1 -10), mine was 30MOhms.
Best of luck!!

checked ground wire, got good grounds. i've run another bottle of fuel injection cleaner through it. still no changes, running like crap. hard running on start and go... but once it's going, just giving it a little gas and it'll run like a champ... push that gas pedal a little too far and it goes to cutting out, spitting, coughing, back firing... anyone else with any ideas.... i replaced the crank sensor about a year ago, when it would get hot, it would stop running...well, a couple days ago i was running around town, it got hot.. so i stopped, poured some water on the crank sensor, no change in the way it runs... so i don't think that's it..... rpm's have nothing to do with how it's running, i can do 70-80 with no problems, so long as i go easy on the throttle.

checked ground wire, got good grounds. i've run another bottle of fuel injection cleaner through it. still no changes, running like crap. hard running on start and go... but once it's going, just giving it a little gas and it'll run like a champ... push that gas pedal a little too far and it goes to cutting out, spitting, coughing, back firing... anyone else with any ideas.... i replaced the crank sensor about a year ago, when it would get hot, it would stop running...well, a couple days ago i was running around town, it got hot.. so i stopped, poured some water on the crank sensor, no change in the way it runs... so i don't think that's it..... rpm's have nothing to do with how it's running, i can do 70-80 with no problems, so long as i go easy on the throttle.
Have you checked the fuel pressure as the problem occurs?

how do i check the fuel pressure running down the road... can i leave the fuel pressure checker plugged up, with an extension, and run it outside the hood onto the front windshield.. that'd work i guess... if it's not raining tomorrow, i'll try it... been raining for 2 days now..

Max, what about the TPS ?,could it have a bad spot?

Sorry ,reread the original post about the TPS.

forgot to mention, if i floor it, trany will down shift, engine will rev... but it sounds as if it's missing a cylinder.

OK, took ignition control module off and went to autozone, they ran a test on it and it came back good. did another volt test on the tps... works fine... did another pressure check on fuel system. left pressure valve hooked up for more than 10 minutes, no drop in pressure... anyone with any more ideas.... please... at a dead end... maybe just junk it... but it runs great so long as you're up to speed and not giving it any gas. thanks, jeff out.

ok, one more time... someone please help.. i love my bonneville, i miss my bonneville... so, i've checked the fuel injectors, they're fine... still got this problem... kinda missing at idle... but will not accelerate. if you barely push the gas peddel down it will pick up speed and will get to 65-70 and cruise there without a problem.. but as soon as you try to accelerate by pushing the gas peddel a little too far, you're in trouble. i've checked the tps with a ohm meter but i'm thinking of replacing it out of desperation. i've also read about the fuel pump strainer collapsing... someone please help, i'm desperate... thanks. jeff out.

I am going through the same problem with my '92 Bonneville SSE w/supercharger. Thanks for listing everything that you have done. The only thing I don't understand is the TPS that you checked. What is it?

By the way, I don't know if it's a coincidence or what but I just put a new battery in today, and it ran better today than it has in a long time. Still misses when I give it too much gas but wasn't nearly as bad.

I have been fighting the same problem on my 95 Bonneville. I thought I had it fixed until last night. I too had a bad coil pack and replaced it. A week later I checked the others and one of them was bad also. I ended up replacing all three. It ran great again until last night. It acts like one of the coil packs has gone again. I will check it this weekend to see. Not sure if the coil packs were root of the problem or not. If I find out anything more I will post again.
04/22/07
Turns out that the original problem I had was just the coil packs. One went back then another and so on. The new problem was one of the spark plug wires was laying on the exhaust manifold in the rear of the engine and it was shorting out. I pulled the slack out of it and the car is running great again. Will replace that wire to prevent a future problem.

The history of my problem is as follows: 1995 Bonneville with 205K miles on it
It started running rough when trying to accelerate. When running at slow speeds or cruising it ran OK. I thought it was the Cat. convertor but it checked out OK. When I checked the coil packs they were reading 6.25 Kohms, 9.5 Kohms, and 6.2 Kohms. I thought the one reading 9.5 was defective so I replaced it. Ran better but then started doing the same thing again. I then thought it might be the fuel pump. I didn't always hear it when I turned the key on. Bought a pressure tester and found that the fuels pump was OK. I had already replaced the spark plug wires so I had the ignition module tested and it passed so I replaced the plugs. No help. Tried to have the coeds read at Autozone and got NO-LINK so they said they thought my computer was bad and the car was running in a safe mode. Bought a new computer and it didn't fix it. I rechecked the Cat. convertor and when I accelerated the vacumnn went to 0. Had that and the resonator replaced but it didn't fix the main problem. I finally decided to check the coil packs again. The new one was readin 9.2K and one was readin 6.2K and the thrid one was open. I put the one back on that I had replaced and it was running great. I bought another coil pack and put it on where the one was reading 6.2K and on the way home it started running bad again. Checked them again when I got home and the one that I had replaced first and then put back on was now open. Put the one that was readin 6.2K on and it ran great again. The next day I replaced that one and it ran great all week until my trip and that turned out to be the plug wire. Moral of the story.....if one coil pack goes bad replace all three because the others will soon follow.

Check the TCC solenoid on the Transaxle. What is does is locks the torque converter at highway speeds for better milage. If it is not unlocking at lower speeds it will buck and caugh and spit and generally run as you discribed. It will also snub the engine when you come to a stop light because it is like not pushing in the clutch in a manual tranny. Diagnosis is tough because the damn thing works when it wants too and sometimes just half way. Running too much with it bad can kill the tranny. The way to test it is to just unplug the connector. That way it will never engage. (gas milage will go down on the highway) If that cures the symptoms, then it could be the solenoid, or the connector, or the wire, or the ground, or the computer sending the signal wrong. It could also be dirt or junk in the valve body ports that are controled by this solenoid. Actually if the transmission oil is low this could effect the function of the lock-up mechanizm.

Good luck:banghead:

Another strange thing is that when i start the car. it is idiling at 2000 rpm, it normally sits at 1000 rpm. when you rev it up it will return slowly to 2000 rpm. instead of dropping to 1000. uncle thinks it the crank censor but i replaced that just last year. when it went out last time, when the car would get hot the engine would die until the car had cooled down. one day it died on me at the dollar store. it was 98 degrease outside and i wanted a coke. i bought a nice cold coke, took a few drinks, poured the rest on the crank censor and it started right up. i wish this problem was that easy. i'm down to trying 2 things. replacing the throdle position sensor or pulling the gas tank and checking to see if the pick up screen has collapsed. someone earlier mentioned something about a traney sensor but i don't know where that would be located...ever since i bought the car, when you let off the gas and the car is coasting you can kinda feel the traney breaking but it breaks in pulses, you can see the tachometer dip when it breaks, it's weird, feels like i'm tapping on the breaks lightly about every 3 seconds. car has done this ever since i bought it, i changed the traney fluid but this didn't help.