after changing plugs, wires, battery, fuel filter, altenator checked ok, air filter. My problem still exists. check engine light was on and code was to replace o2 sensor, did that. Yukon shuts down while slowing down to stop (sounds like it is losing fuel. Idles at around 400 RPMS. what could this be?
Shutting off at idle on 2003 GMC Yukon XL Denali
by wdalecole in Yulee, FL on December 19, 2010
ANSWER by DaveJM , December 19, 2010
Couple thoughts - first, the "code...to replace o2 sensor" sounds like a poor interpretation of a code. What code was it? There are no codes that tell you to replace a part; merely codes that help you identify symptoms so a good diagnosis can be performed. Second - my guess is that your code was related to lean fuel running, which is measured by the oxygen sensor, which is why many just jump to the conclusion that it is bad. Chances are you are running "lean" due to a vacuum leak somewhere, which is causing your stall and your low idle. Check for that -- good luck.
ANSWER by scollins05 , February 20, 2016
Sounds like the same issue I had with my 03 Yukon. I cleaned out the throttle body and it cleared it up. Carbon builds up on it so you need to use a brush or something to get in there to clean it out.