Jwilk

Brandon - I had the exact same issue. Runs smooth when you're off the gas, right? You will probably notice that the truck will "lurch" while shifting through 2nd-3rd, and 3rd-4th gears soon. Took mine back to the dealer and they agreed there was a problem. They couldn't figure it out, so they called in a GM field engineer. They came to the conclusion the torque convertor was out of balance, and chose to replace it. Worked great for 5 days. Then all the issues came back. This time, at the direction of the field engineer, they disassembled the transmission - still couldn't find any issues. So, they chose to replace the entire transmission (which included a transmission control module & another new torque convertor). So far, it's running fine. I had about 7k miles on it when this first started. Put about 2k on it since the new transmission. Each time, the dealer had the truck for about 2 weeks. Everything was under warranty. Haven't notice the RPM thing, so I can't help you there.

Silver Spaceship - does the vibration feel like rumble strips for about a second? Thats what mine was/is doing. Symptoms sound very much the same. I also experienced a slip between 2nd & 3rd gears as the truck was accelerating. My truck spent 2 weeks with the dealer as they couldn't figure out the issue. They experienced the same vibration & slip, so there was no denying it existed. No error codes were present. They eventually called in a field engineer who determined the torque converter was out of balance. Their solution was to replace the torque converter. Had it back for 5 days, and it is starting the vibration & slip issue all over again.