I have a 2012 yukon that seems to have a bit of a high idle after I drive it for about 15 miles or let it sit running for a little while. It usually runs about 600 rpm but after a bit of driving and I stop at a light it runs about 800 rpm. If I shut it off and start it back up it will return to around 600. I know its only a couple hundred rpm but just kind of concerns me that a sensor or something might be going out. I have 82k miles on it.

 

I did not see you supply any engine info so I took a WAG and looked up info for a 5.3 engine. There are maintenance steps for these three items: First the MAF, https://www.rockauto.com/en/moreinfo...502527&jsn=898, then the MAP, https://www.rockauto.com/en/moreinfo...502527&jsn=903 and then the throttle body, https://www.rockauto.com/en/moreinfo...502527&jsn=914.

All these can be cleaned and can be contributing to what you are saying. The cleaner(s) can be had at a parts store and make sure to follow the directions. You may also have a vacuum leak. How old are tune related components?