Ok, i have changed rotor,cap,wire,plugs,pcv valve. I have a 1996 blazer 2wd 4.3l vortec v6. When its cold it idles fine. But after its warm it had a rough idle. When in the high rpm's its normal, accels great. I am now wondering about the egr valve. Cleaned it yesterday, and watched the pintle move. Not sure if the diahpram is bad. Any ideas to point me in the direction of getting this ghost code cleared. Also the cat is fine (removed it). I beleive this year used the famous spider injector. I just hope it dosnt come down to buying this part and it be something retarted. Any help would be great.

 

Check your distributor shaft for play. Take the cap and rotor off, and wiggle it side to side and up and down, if its got some play, its on the way out. Random misfire is mostly cause by a wobbly distributor shaft, its really the only part that can make a random misfire.

 

this may prove useful.
https://blazerforum.com/forum/tech-articles-diy-29/posted-obdii-trouble-code-diagnosis-26408/

 

Thanks for the pointers will try tonight and see what I find out. Will let you know if this is the problem.

 

But im just confused..... it idles great when started and its cold. After she heats up its a rough idle, stumbles until around 1800 rpm but not bad. I blocked off the egr valve last night, no change. I also just read, from the thread from 84blazers10, a guy has the same issues. When he replaced the icm he forgot diaelectric grease. Says he put some on and bam, fixed the problem. I did notice the grease on mine was a little old, and dryed up looking. Does this seem like a logical issue?????

 

Had the same problem and code listen to ohsofly my upper bushing on the distributor was bad. It would idle perfectly but as soon as you tried to drive it,it would run like crap and run good when you come back to idle. There is some up and down movement on your distributor to allow for heat expansion so when you throttle up your distributor and rotor move up and if the bearing in the top of the distributor is bad this is when it is ging to run bad and set the code.

 

Yes I will try tonight, didnt have time the other day. But it only stumbles up until 1800 rpm after its warm. When its cold it runs great. I will still try this but im runnig short on patience and this is the longest its ever taken me to diagnose an issue on a vehicle!!!! Thanks to everyone so far.

 

After its all warmed up and shut it off, does it crank for a bit to start again? My blazer had a P0300 with hard start after warm up. Fuel pressure regulator was leaking fuel into Cyl. 2,3,5. Replaced that and ran like a charm.

 

Yes! Bingo, it does crank for a bit then starts right up idles a bit rough. But its just all to odd bc sometimes it will start right up after its warm but not very often. Where is the best place to put in a gauge so i can check before purchasing a new fuel pressure regulator. Im sure i could figure it out but other peoples advice is helpful. Thanks for the tip. Will get to this by the end of the weekend.

 

Check your distributor first it will not cost you nothing. There is a scharader valve on the fuel rail. Check one problem at a time simtons maybe the same but don't let it side track you check the things that you can do right away. If you don't know how to check fuel PSI obviously you don't have a fuel gauge and you are going to have to buy one or find somebody who has one. Check your distributor first.