Ok this doesnt happen all the time. It only happens every once in a while on start up. When it does happen it sound like it is only running on 2 cylinders and i have to hold it at about 2 grand for a few seconds and then it will clear and smooth out . It will run perfect then. It drives fine. Its a 94 lt1. Last year we had the same problem, so this winter i replaced the opti with a partsladi one(FTW), new NGK tr55 plugs, 8-8.5 mm plug wires(look fine, not new), MSD coil(not new,also tried the stock coil). The ICM is the only thing i have never replaced. Could the ICM be causing this?

 

Jim I don't know if you have done it or not but I would verify the injectors are firing individually, a noid light helps alot! The local parts store can testthe ICM for free and that only takes about 15 mins to take off and replace so that would be an easy etst to rule it out. It could be a number of things really, just a lil gremlin your gonna have to catch and keep in a bottle

 

Thanks Jack. I wouldnt know were to get a noid light, let alone know how to use one. The fuel injection thing is still kind of new to me. Im old school (carberators FTW)

 

Ever have a cold humid morning when the thing would not start. I suspect it's the same thing. The opti is wet inside. Happens to me all the time. Later the same day after it warms up. Starts and runs fine.

Wouldn't expect the PCM to drop out signals to the injectors only occasionally. Although a connector issue could be what was described. If that were the case, wiggling wires while it's running ok MIGHT show the problem but I doubt that's your problem.