I have the same problem with my 2016 CC short box.
Last time I took it to the dealer they drove it and of course they couldn't find anything wrong.
Gm rep some help.
2016 Sierra CC Texas Edition with a denali grille
22 inch Gima Paradox
305/45/22 yokohama tires
2 inch Mcgaughys lowering shackles
Airraid modular intake tube
Met Powr-flo Mass air flow sensor