95 Z-28 intermintent problem
 

Any help is greatly appreciated. I have been to every auto parts store in 5 miles and nobody can scan the codes for me. I can start the car and it runs fine for a while. I drive it and it runs smooth. If I park it for a bit and come back out, once in a while, it will spit and sputter and want to die on me. Sometimes it will die but I can start it right back up. While it is doing this, the tach is bouncing all over between 500 & 3000 rpm even though the engine is not reving, just sputtering. This happens when it is completely dry outside and has been for a while so I doubt there is moisture getting anywhere. The front and rear mains on the engine, rear seal on the trans and the water pump have all been replaced in the last 6 months. The service engine light comes on do I know there is a code stored, I just can't get at it without spending the stupid amount of money for a dealer to plug in his scanner. I know this kinda sounds like an opti spark problem but I the smooth running makes me question that. Do I just need to bite the bullet and get the codes scanned by the dealer?

if you have access to a obd1 scanner (not code reader) then you can do this

otherwise i would say its most likely the opti or ignition control/coil module although im sure theres a few other things that could cause it like failing ecm/pcm. heres some info to test some of the ignition

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I've had a bad opti before, and the rpm's didn't bounce around at all. A bad ignition module however can make the tach jumpy. That's what I'd suspect, with it running crappy and the jumping rpm. That's best guess though, without checking the error codes.

Problem fixed
 

I replaced the ICM with a spare my cousin had from a rebuild and I found a vacum line from the opti disconnected. Runs like a top now. Thanks for all the help!

i would say the icm was failing. vacuum line is just for vent.