I have a GMC 2010 Yukon Denali XL, when I start the car, and have the engine running idle. The engine runs a little bit rough and every 20 seconds or so the engine starts to rev up and down from 400 to 1100 rpm, kind of aggressively in my opinion. Sometimes, whether I don't move the vehicle at all or begin driving, the Stabilitrack and engine light turns on; engine power is reduced and I see the messages, service traction control and Stabilitrack. When engine power is reduced, I can't drive above 20 mph even when the pedal is to the floor, and I have to turn off the engine for at least a couple minutes to have the engine run like normal again.
When the engine is running at operating temperature, 210, the problems seem go away with the engine light still on however. Also before the engine reaches operating temperature, there is a delay in throttle response. The engine will put out power more than a second after pressing the pedal.
This issue has been going on for two or three years. Spark plugs have been changed, oil is changed regularly and oil level is correct right now.
I don't know if there is a problem with the engine or the fact Stabilitrack is malfunctioning that's causing these problems.
Any help is appreciated, thanks.
Update: The car has approximately 90k miles on it and has a 6.2 liter engine. Additionally, I learned about the symptoms of bad engine mounts which these symptoms seem similar to the symptoms my car is having. I don't know if it's the engine mounts yet, I will need to read about it more.
Update 3/19/2023: I cleaned the MAF sensor a week ago, at that point in time the symptoms seemed to have eased a little bit. I haven't been getting any reduced engine power occurrences lately. I don't know if cleaning the MAF sensor helped or the weather is starting to get warmer. I typically drive the car only on the weekends and not everyday.
The engine light came on again last Thursday, so I took that chance to go to an auto parts store and get the codes. I got the codes: P0300 - stored, P0121 - Permanent, P0121 - Pending, P2135 - Stored, and P0121 - Stored.
Reading about these codes, it seems the issue is revolving around the throttle body, throttle position sensor, or a bad connection coming from the throttle position sensor. I also want to add that another symptom is that sometimes there is a concerning sound when accelerating after the engine recently started up. It sounds somewhat like grinding or something blocking another part from moving. My guess is that the throttle body is having a hard time opening when I press on the gas and that might be a reason for a delay in throttle response?
