I have a 99 G20 (42,000 mil) When I start it up in the morning, it revs up to 1700 rpm and it takes at least a minute for it to get down to 1000 rpm. I live in s. california, it's pretty warm down here, but fairly cool in my garage overnight. Is it normal for the rpm to be that high when the engine's completely cool? I asked a mechanic and a guy at the dealer, but they both seemed to give me vague answers. Any thoughts?