WillySea

My 2021 AT4 with the 3.0 diesel has a shuttering issue as well. This does not always happen, but sometimes when I’m in cruse control at 45 mph and run for about 5 to 10 minutes, then move the cruse selector up to 55 mph I get a violent “bump bump bump” shutters. It feels like when a universal joint goes bad, but the RPM’s stay the same (always around 1400 to 1500 RPM), or go slightly down, so it’s not the clutch slipping or the RPM’s would go up. i have gone to 2 GMC service centers and had two mechanics ride with me to replicate the problem, of course it wouldn’t happen. It has happened once with a rep inside on 3 different drive. Because it can’t be repeated consistently they can’t fix it. Anybody got any insight. Thanks in advance.