94 Z28 LT1 Camaro. Intermittent stalling/starting problem. Been haunting me forever.
Typically my car will start fine when it's been sitting overnight. Then I'll drive to the gym which is 2 miles away. The car will sit for the time I'm in the gym maybe an hour and then won't restart. I'll let it sit some more, crank it and eventually I'll get it started. Then it will stall at idle. I'll let it sit, get it started again and this time it will drive a short distance before sputtering on acceleration and cutting out. Sometimes it won't sputter, and instead will just instantly cut out and I'll coast over to the side of the road. I'll let it sit for 10 minutes, start it up and move a half mile down the road before it cuts out again. This cycle repeats itself. If I can't get it restarted which sometimes happens I'll let it sit overnight come back in the morning and drive her home. The car is not throwing any error codes. The problem seems to be getting worse as time goes on. My ignition switch is getting bad as in it's becoming hard to turn and I have to play with it, but I don't think that would be the issue.
What I've done to fix the issue:
I've replaced the ICM. The Optispark is new and god forbid not failing me. The starter is new. Battery is new and charged. Spark plugs were changed with the new optispark. I had it in a shop for 6 weeks and they couldn't replicate the issue. (Of course.) They informed me the fuel pressure was good but the car has a small misfire and doesn't seem to be getting the horsepower it should. The engine has a slight shake to it, I assume that's the misfire they were talking about.
What I am going to do next:
Replace and test some cheap parts like the fuel pump relay and ignition coil, return the ICM I just bought, and hold off on taking it to another shop. This is personal. Besides anytime I mention the problem is intermittent to a mechanic over the phone I can hear an instant tremble in their voice.
So good people of SE, any idea what is going on?
I thought for sure it was the ICM.