
I have just got my new car, and its mint apart from one small problem.
Intermittently, the Idle speed rises and falls. From cold, once the negine is running, it reaches aroun 1600rpm (normal) and drops slowly to around 900 - 1100rpm. However, after driving aroudn for a bit on a warm engine, the idle goes up to around 1600rpm again. I have reset the ECU, (unplugged the battery for 1/2 hour) and that has made it a little less common than before, but it still happens

Could it be the throttle body itself? maybe the butterfly has a load of crap on it and is staying open, or is it something to do with the electronics? Thanks in advance guys :S