For those experiencing this, can you describe exactly what you're feeling? I just bought a 16' XL Denali a few weeks ago. When stopped, I notice a little vibration or "gurgle" that happens every few seconds. However I'm not seeing any movement in the tach when it occurs. I wasn't sure if this was normal behavior for the 6.2, or if this is the rough idle that others are describing.
It's pretty much what you've described. If you've ever had a vehicle shut off on you at a stop. It's kind of like that, but not to that extreme.
As far as the tach, it is barely noticable. But it only happens under 500 rpm's.
I used to have a Chevy Colorado 1st gen that did something very similar, but a throttle body cleaning took care of the vibration completely. As a matter of fact that's the first thing I did to this vehicle, but it didn't do any good.
Had I not had a 2016 Tahoe before this one, I probably wouldn't be making such a big stink about it. But there's an obvious difference. Seems like a quality control issue. "These engines just run like this", is a bunch of BS. I've experienced what this engine is supposed to run like first hand.
We'll see what the dealer tells me tomorrow. The service advisor already hinted at the vehicle being within the manufacturers acceptable vibaration level.