Engine Performance problem
1993 Ford Aerostar 6 cyl Two Wheel Drive Automatic 170000 miles
engine idles at 2000 rpm, throtle body butterfly is closed and does not seem to have a vacuum leak. Started when I had alternator replaced at local shop. They said it was a cracked hose from the air filter to the throtle body and taped it up but still idles fast.
First, you never, never tape a hose up, you replace it! As for your issue, it does sound like a vacuum leak. The best way to find one is look for the area that has a loud sucking sound or spray carb cleaner all around the engine while it is running, if the idle increase then that is where your vacuum leak is.