Could be a problem with the idle control valve? Not sure though, and a turbo timer usually works when you have turned your car off, so you set a time on the timer for the engine to run for it to cool the turbo (s) down. Do you have a turbo timer? Anyhow this wouldn't explain the rev's shooting up to 2000rpm at idle. I'm sure someone who knows the answer will pop up and help you out mate. You might wanna post this up in the techincal forum?