i know they did plugs at the track on saturday b/n races. as for cap and rotor i'm not sure, but i know i suggested it to em on saturday at the race so hopefully they did it. I know when my car was having misfire probs though it was in the lower rpms and mine was from cap and rotor. also i know it's not fuel lines or fuel filter b/c they had to run new ones after they bought the car and it's ran fine at one point since then.