alright, so heres the problem. Care died on me last night while it was running. Would not crank back up. Came back an hour or so later and it started, but ran rough. left it over night and came back in the morning, the car started fine and ran fine. Called a friend and he said it sounds like the coil, or the coil (ignition) module. I drove the car for a while and it started to run rough again. i bought a new coil and connected it, but the car still ran rough. So then i bought a new module and installed that. The car ran great for a while but i let it sit and get warm again just to make sure. Then it started to run rough again. So now i have no idea what to do. Is it the opti spark. i wouldnt think it would be since it runs fine when cool, but rough when it gets hot. HELP!

 

I have a 94. Pretty much same issue. Shut down towed home ,replaced opti spark with ac delco reman. Now starts runs rich and shuts down. Replaced icm spark plugs wires. Original opti spark looked like it was found in bottom of the ocean. Car has 18 k miles. Has code h71 and h15. I’m sending opti back and really want to upgrade to vented.