Ok, heres my situation: I bought my car 2 years ago. Its a 91 z28 w/ l98 and almost every option (excl leather). Its a fairly low mileage car at 46k. I have begun adding some go fast goodies. I added flowmaster cat back, removed air baffles and got k&n's, new taylor 8mm wires, all new gaskets, cap, rotor, spark plugs. I also added a new sound system .My car's "SERVICE ENGINE SOON" light would keep coming on. but driveability was never affected. No code could be pulled. The engine light began coming on more and more frequently. Then. when the light came on, the car would idle extremely roughly, and would idle itself out. I took my car to a mechanic (friend too) to see what he could do. He ended up replacing the ECM. Car ran beautifully w/ new computer but then after about a month my car had the same symptoms. I got another ECM and plugged it in and seemed to have solved the problem again. After storing my car for the winter i recently took it back out. Car ran great for a week and then same problem again, this time on a few occasions the car would not start. With a rap of a hammer on the starter it would then start up. So i replaced the starter and seemed to start engine fine. Then I go to fill up at the gas station and the car would not start. Got it towed back to my house and now need help figuring out what is wrong and what to do to get it running better than new. Also, when the engine light was on and it didnt idle rough the car was very sluggish, as if there was a delay before acceleration. Any input wil be greatly appreciated.