I have an '04 LLY Duramax that seems to have a strange pulse in it as though either fuel starved/recovered or a high-lift cam action (old racing days never really go away ). It is prevelant at the top of the pedal while cruising or at idle. Not noticable during acceleration or decleration. Strong enough at idle at times to lurch the vehicle while brakes applied. There is no discernable pattern to when this occurs, but it seems to be stronger at cooler, damp weather than not. It is alway somewhat present at any temps and weather and engine temperature seems not to affect its occurance or lack of it. If anyone has experienced similar conditions, what have you done to correct it? Dealer Service Tech says GM Acknowledges the problem, but has no official repair to offer.