Have 99 Yukon 2wd 5.7 135,000 since new and most of time engine will not slow until I apply brakes. Idles correct, no service light or code. Years ago dealership replaced TPS and worked a couple days and returned. This also can happen if I pull say the MAF or other sensor wire, run then reconnect, it may decelerate properly for a day then back again. It comes and goes on its own. In a parking lot, engine will run 1500 or more RPM until I apply brakes then it idles properly. Will decelerate all the time by putting in a lower gear with higher RPMS - like vacuum has some affect. Driving it will take 3 blocks in D3 to slow from 40 MPH to maybe 30. Will decelerate when driving, if I shift to neutral and back to drive. Also has a 3 second lag period from releasing throttle to engine slowing.(maybe normal?)Thinking MAF or MAP?
99 Yukon desn't want to decelerate most of time on 1999 GMC Yukon
by John Baxter in Fresno, CA on January 07, 2012