I have a 2001 galant, when it is parked the RPM goes to around 1300-1500 but will go low when put on Drive or reverse or the A/C is on to around 700 which is the normal i believe. I've changed the sparks, and the oxygen sensor, and the head gasket. but nothing changed. If you suggest something about the idle please explain what you mean??? and please give me a solution.