1992 Ford F-150 • 5.0L V8 4WD Automatic • 165,000 miles

My ford f150 is running at a high idle its starting cold and runs as high as 2500 rpm it will kick down to like 1200 to 1300 rpms I cant find a vacuum leak. I changed the air idle control valve to tell you the truth it seemed to make it worst. In gear its running at 1100 rpms I don't wont to be a parts changer what do you guys think could be causing this problem. Other than that the truck runs great no misses lots of power and no check engine light.
February 17, 2014.

It sure does sound like a vacuum leak, but if your sure that there aren't any then I would suspect a faulty t.P.S. Sensor or carboned up throttle body.

Feb 17, 2014.