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?

  • I don't think a Stabilitrack problem alone would cause the issues you're seeing. I think it is probably a symptom of something bigger. How many miles are on the Yukon? And this has the 5.3L, 6.0L, or 6.2L engine? (I don't remember what comes in the Yukon XL of those years.) Commented Feb 26, 2023 at 22:54
  • @Pᴀᴜʟsᴛᴇʀ2 Sorry for the late response, I updated the post to answer to your question. Thanks Commented Mar 6, 2023 at 3:02
  • 1
    This wouldn't have anything at all to do with motor mounts. Your engine is surging due to an issue which is commonly having something to do with the intake tract and/or the MAF sensor. You might try cleaning the MAF and see if this improves things for you. It might also have to do with there being a discrepancy in how the throttle position is adjusted, though I believe your Yukon has a drive by wire (DBW) system in it. Commented Mar 6, 2023 at 10:35
  • Any check engine codes?
    – rogerdpack
    Commented Mar 7, 2023 at 5:04

2 Answers 2


After some research and thought about this, it seems that the most likely issue was something to do with the throttle body or position sensor. I decided to clean the throttle body first and see what happens. When getting to the throttle body I found that the inside was very dirty and cleaned it as thoroughly as I could and then I put everything back together. I've been driving it for a week now and I haven't had any of these issues anymore and the car seems to run fine. Thanks for everyone's help.


I had a similar problem on my 2003GMC and I found it was the throttle body. If you change it out I found that it doesn't include the body to motor gasket. This is a MUST include! Even if the gasket looks good, don't just clean it! Yes you could wait a few minutes and restart but could only get another few miles before the reduced engine power returns . Without the new gasket it looks like oil and or water still seems to seep by and the problems are back. Good luck.

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