Hey Scotty. I have a 2020 Silverado with the 5.3 6spd with 13,000 miles. I have a bad vibration at 30, 40, and 50 mph on light acceleration when the RPMs drop to 1,000-1,500. The Dealership ruled out torque converter, transmission, motor mounts and transmission mounts. Could it be an issue with the Active Fuel Management? Here’s a video of what I could capture. https://youtu.be/ne5TRlIrQpg
Have they checked for an unbalanced drive shaft? I have heard this is a problem on a number of vehicles. With the vehicle on a lift, they should be able to check for that.
Yes they checked driveshaft, tires, suspension, transmission, torque converter, replaced camshaft actuator, motor and transmission mounts. If you watch the video, the rpms drop and the vibration starts. It’s puzzling a lot of people.