Hi guys, I have a 2011 Yukon 5.3. I recently replaced the throttle body because after cleaning the original one, and doing a relearn, it would still stick. After installing the new one, we opted to let it do the manual relearn by driving about 250 miles. Took a trip upstate and back, with various accelerations and decelerations because the highway was so backed up, still nothing. Came to my shop today, and my coworker threw his scanner on the car and did the idle relearn, and it still doesn’t do what it’s supposed to. It still sticks, it downshifts very hard when coming to a stop, and sometimes stays stuck above 1800 rpm when thrown into park/neutral. What could this possibly be?

 

Keep in mind the accelerator pedal is also part of the throttle control system.

Check that the pedal isn’t sticking or dragging on its own as well as not getting caught on the floor mat.

Are there any codes?