I have a problem with my 99 Yukon with 80,000k, in which she misfires at idle when fully warm (ie after a ride on the freeway,10 mile plus trips in town). We have replaced in order; plugs, dist cap, wires, exaust doughnuts, air filter cleaned (k&N), fuel injectors,intake gasket. I had it smoke tested for vacuum leaks with nothing found. After all the updates and tests, it still shakes like a Harley at idle while in drive at a stop light. when it is cold, she runs good with no idle problem. Anyone experience any similar problems? Any help appreciated, Tnx.

possibly the coolant temp sending unit? or what about the crank sensor? it sounds like a sensor is breaking down at high temp...

possibly the coolant temp sending unit? or what about the crank sensor? it sounds like a sensor is breaking down at high temp...
Thanks for the reply. The engine seems to run ok otherwise, my mechanic believes that there is some engine wear in the valve train. With a roller valvetrain, how could it be? Thanks again, Steve.