My 2009 Tahoe dies when sitting in traffic idling. The starter is disabled for about 3-5 minutes before she will crank back up. Just drove 250 plus miles on the interstate with no issues but left it idling when I got home and sure enough she died and was disabled again. Immediately checked temp with gun and temp was 185. Have seen three major parts stores and put on machine and a Visit to a diagnostic tech today to hear take it to the dealership. Any help ?

 

My brother had these symptoms on a Mustang and it was the computer and something else electrical. The mechanic he took it to found the issue real quick by connecting a computer to it. It's fixed now and runs perfect. He messed with it for the best part of a year and couldn't figure it out. He probably wasted the price of the repair throwing parts at it. It had something to do with how heat affected the circuits, etc..

 

The Electronic Throttle Body on these likes to fail. GM had a recall/notice about them, and covers it under warranty for so many miles. Else it's a $120 part I think.

I don't know if it's your issue, but it does control engine speed, including at idle.