98 ENVOY fuel/electrical help?

Hello everyone! im new to this forum.we have a 1998 GMC envoy that has a 4.3 vortec i belive.just hit the 150,000 mark and its having some problems. probably around 135-140k the engine started to miss noticably so we did a basic tune up. plugs wires distributor rotor/cap. seemed to work a little better for a couple months. it started to slowly progress to get worse. Very Very noticeably around the 1800-2300 RPM range its really hit and miss.up untill one day it finaly just died and wouldnt start back up. we had a tow truck come and get ready to tow it and he took his chain and went and hit the fuel tank and it started right back up and was able to drive it like this for another month or so. up until i died again. so my parents had the fuel pump replaced. it worked good for a few weeks then the symptoms of sputtering around 1800-2300 rpm range started to come back. took it down to auto zone and had them hook up a error reader thing to it and gave off a code p0300 or something like that whitch is a random misfire in a cylinder. i check the fuel preasure the first time and got a reading of 56-58. replaced the fuel filter and that raised it to 66 with key turned over when started it would go down to 63 maybe a little below depend on the throttle.but being below 60 shouldnt cause it to stall out like it is. after it stalls out its really hard to start it back up if you can even get it to restart at all.I'm not exacly sure how to check the coil on this thing since the coil looks nothing like the one in the chilton manual we have. the only thing i could check on it was if its getting proper battery to it and it is. reading around 11.6.the only other things i could think of is possably the fuel preasure regulator,the cmfi and related stuff or faulty electrical connectors to fuel pump? oh yeah we check out the air intake and it was CAKED with black crap. i mean REALLY BAD so we took and cleaned it with carb cleaner. made it smoke for a bit after we could get it started but still the same symptoms.i kind of randomly went at this frustrated with the problem working with it in the snow so forgive my bad spelling/typing skills.

well i just took off the distributor/rotor that we replaced about4 months ago to see if that was the problem because it started to back fire after we sprayed the carb cleaner in there. the rotor had a build up of metal it looked like so i sanded it off. the contact points on the cap were white and it almost looks like 2 of them are deformed a bit like the metal missing from them is on the rotor. i cleaned everything took it for a drive and seems to be fine but a couple instances where it just shut off for a split second while steady throttle then continue on like nothing was wrong. i forgot to mention we have a problem with getting the key out of the ignition after shutting the engine off at times.

Welcome to AF, basics here when it dies and will not start what is the FP and do you have good spark?

fuel preasure at the schroder valve is the same 63-66 with key on 60-63 when started. how would i check for a GOOD spark? i have a ignition spark tester hooked it up to the coil and grounded it to the plug and it was showing a spark. not sure if its good or not

::edit:: i used something like this to test the spark again http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=36258
but the one i have has 2 alagator clips and 2 points where the spark meets in the middle and a "cylinder" to create preasure to act like the spark was in a cylinder. i didnt use the preasure part but i was getting a constant purple color spark comming the the coil

checked the fuel pressure today with key on. it was barley reading 59-60. i started the leak down test and it indicates that i have an leak somewhere in the system. I let it sit at its max psi it could get (60psi).it took less then 5 mins for it to get below 55PSI. its not the fuel lines because they still look new. where can i buy the 3/8 shut off tool required for the rest of the test or parts to possibly build one

where can i buy the 3/8 shut off tool required for the rest of the test or parts to possibly build one

Never mind! i went down to my local hardware store and found pieces to make one. fwi just take your fuel filter down to say home depot or local hardware store and go to the plumbing section and have at it with the 3/8" fittings. i will take pictures of what i bought to make mine and post them later

well i built a shut off valve tester... got home getting ready to do the test and decided to test the fuel psi again. turn the key to key on 66 psi then some click in the intake and dropped it to 62 psi right away. i let it sit there for 5 mins and didn't drop below 59-58. WTF GIVES!?!?! this darn thing has a mind of its own i swear... Long story short. i drove it to a friends house, it did perfectly fine. next morning i tried to start it up started the same crap. got under the hood wiggled some wires it started right up. went back to the hood to shut it and wiggled the wires just for he heck of it. and the BATT in on the coil wire was the whole problem of the car shutting off/getting crappy idling etc. the connectors in the plug were spread WAY too far apart so i took a small flat head and pushed them together to make a REALLY tight fit. problem solved so far.i wish i had a camera to take pictures but i think i messed up the sensor in my 8 year old digi cam when i was taking pictures of me welding so it would only take really efd up pixelated pictures. Ill report back in a week or so if im still having fuel problems. this -2 degrees outside isn't very fun to work in with cars.

I have a '99 with similar problems. At one point I replaced the distributor cap and it fixed the problem, it had a hairline crack that fouled the electrical signal. I am having the same problems again. Replaced plugs, wires, cap & rotor - still no good. Fuel pressure is fine.
A friend of mine told me that it could be that the distributor weights are dirty??? So, when the weather warms up a bit (18 degrees and snowing) I will pull the distributor and check it out. Does this sound familiar to anyone out there?

.....A friend of mine told me that it could be that the distributor weights are dirty??? Does this sound familiar to anyone out there?.....

Sounds all too familiar however, distributor vacuum advance units, counter weights, and springs were eliminated back in the 1980's... about the time computers started controlling ignition timing ;) The only things in there now is a Hall effect switch and a rotor. Some engines don't even have a distributor.

Well as far as my rotor and cap being efd up too. it could have been the problem the whole time we bought some cheapo distro and rotor and about 2 months later i took it off and found the the rotor contact point actually had a little extra metal so i sanded it off. it looks like to contact points on the cap look deformed or worn out. i need to get OEM from the dealership (so i hear) any one know the part number?