I have had my truck in 3 times so the dealer could check out a vibration I'm having. They dont seem to know what it is. I feel a vibration at idle around 550 RPM. If I push the gas a little it seems to smooth out. The vibration comes back around 1100 rpm then smooths out again then back at around 2200 rpm. The dealer had a TSB about the electronic module needing to be reprogramed and they did that but it did not help. Then they did some adjustment with the engine mounts but that also did not help. It seems to me that the engine is out of balance. Has anyone here had this problem that has been solved? I would appreciate any info because I'm taking it back to the shop next week.