When driving the car,and accel.the car will bog down,stuttering and misfiring.I ease up on the gas and it will stop doing it.Its a 94 Z28,LT!,auto,shift kit,headers,K&N air flow,has a MSD and flowmaster exh. also.It doesn't do it all the time.The headers have the oxy. sesors on it and they have been put on properly.The pipes come together on the bottom,with a new cat. converter,thanthe exh. goes to the flow.I would appreciate any help from anyone that has had or heard of this problem.Thanks Keech

 

Sounds like its time for a new opti spark.