Ok so I have a 99gt and my service engine light came on again. I ran the codes and I am getting the same code p0303 misfire. This is the third time this has happened. My question is do I have bad heads. I've replace the spark plugs and coils 2 twice. MAde sure they are tight. I also just had my clutch replaced (spec 1) after the car has been sitting for a month (not sure if that has anything to do with the prob.