[Michael_Price1990]

Pulled out the old spark plugs. and cylinder one had a spark plug. With a crack in it! no idea how. they were in it when i got it a few months back. put in the new set of plugs. and wow... it is driving like a whole new car. feels likes its gained 80HP. takes off way better now. but after the fix. a new problem has occurred. (of course) now when i start the car, idles fine. but then after driving it hard and stopping. it idles around 2,000 to 3,000 RPM. it will slowly fall back down when stopped but only to about 1,900 RPM. this was not a problem before. idled great and quite around 1,200 or so. i'm about to unplug the battery to reset the ECU. but if that dosent fix it anyone know what els would cause this issue?