greenbar

I've read over a lot of the posts from this page, and it seems what I have going on is slightly different. My truck rides fine at high speeds, no shacks or rattles. It's low speed, mostly low or light throttle that I get a almost "torque converter" feel like it's slipping slightly in and out. my passenger can't feel it, but I feel it in the pedal and in the driveline. Is this common or considered "acceptable" ? I don't know if it's maybe my truck needs to be broken in (350 miles on it ) or what. Any advice would be great. 2015 Sierra SLE with 20" wheels