Christian Probably the little black idle control computer behind the drivers seat, has two connectors. When it goes to the high-idle condition, reach back there and unplug it. If the idle settles down (or even dies) the box has failed. Dave --- In dmcnews@xxxxxxxxxxxxxxx, Christian Williams <delorean@xxxx> wrote: > Hi guys, > > I was holding off on posting this problem until I had my o2 sensor > replaced, which I did this morning. > > The problem is that when I start the car up, it idles fine. After driving > 25 minutes on the highway to work though, it idles around 1500 RPM. I've > > What else should I check? > > Thanks, > Christian