2020 duramax truck jolting while towing

[bryant87]

i have a 2020 2500HD duramax, while Towing my Camper roughly 12-13K, my Truck start a hard jolt while cruising down the highway, has anyone else felt this? started out doing it above 70, slowed down to 65 after a little while start at 65 then down to 60, 55 and so forth, never during accelleration or while slowing down just while cruising, faster the speed harder it hits, feels like something wants to lock up, thought maybe the camper but unplugged it and still the same issue. it's at the shop now but the only thing they are thinking are possibly a ECM/TCM update.

 

 

[bryant87]

Update: back from the shop and still doing this but now noticing a rough idle and noticing it driving without a load also. its back at the shop, supposedly they already checked injectors and dont believe they are the issue, has anyone had this same issue?? 

[bryant87]

Still having this bucking issue, getting worse, feel it on everyday driving instead of just while pulling my camper, could this possibly be rear end or traction control issue? did a transmission flush and filter change anda that did nothing at all to help