This is in regards to GMC bulletin #pip4112J : sag or hesitation on acceleration (normal operation characteristics) - (Jul 21, 2011). I've been having this problem since day one and took the SUV to many dealers but dealers could not verify the concern until now. The 2008 GMC Yukon XL denali would stop accelerating for 2-3 seconds when the gas pedal is pressed. Most of the time it is when I am trying to pass a lane, trying to enter highway, trying to climb a mild hill or trying to avoid a potential accident. After the delay, the transmission would down shift and I think it down shifts to either 1st or 2nd gear causing the SUV to roar like crazy and shoots out like a cannon. I had an incident where the cops gave me a warning with the lights and siren probably thinking that I was driving recklessly. There were also incidents where I've had the gas pedal pressed down about 80%-90% trying to climb a mild elevation and either the engine and or transmission started to choke. It was so bad that the denali almost came to a full stop. You really have to experience this on your own to understand how scary and nerve wrecking it is when you have vehicles about to Ram you from behind because the SUV simply would not accelerate. Many times, I had to swerve back in to original lane in fear of causing a serious accident. Because of this, I don't even let my wife drive the vehicle. Service manager was kind enough to research on this matter and found bulletin #pip4112J and he can't really do anything. I've been explained that due to large power from the engine, he has seen the rear of the vehicles break apart. I fully understand the service manger's position on this but I think this is a major safety concern and someone can seriously get hurt by this.

- Sunnyside, NY, USA