TimsLT1

So I replaced the ICM with an identical GM unit. Car starts right up and runs beautifully... for about 5-6 minutes. Then it tries to start and stumbles on the next crank followed by no-start. I have power to pink/blk and ground to blk at the icm, but no fire from the coil. Once it cools off it does this same process over and over. Any more ideas? Could it be anything to do with the Opti that I just replaced? I had a very rough Opti jumper harness which I've replaced now. If there was a short across pins to the optical pickup could I have ruined something? Out of ideas guys. I'm going to go crawl into a hole