A few days ago I had a new MAF sensor installed in my 2000 Grand Prix GT. It fixed my initial problem, but now when I start my car it idles at about 2000 rpm, and then goes down slowly. I put it into drive and it acts fine, no problems as I'm driving. If I stop it and start it again when it's warm it doesn't do it. I'm wondering if this is a precursor to another problem....