My Cousin just bought a 2006 2500 with 96K on it, was used to tow a travel trailer by the PO, its having problems with the trans shifting between 1st and 2nd, It doesent want to shift by itself and you can't get it to shift manualy, have to bring the RPMs up to get it to shift and when it does shift it shifts really hard and fills like its missing second and going straight to 3rd, what could be wrong with it? I'am a manual guy and don't have much expierience with autos.

 

There was a TSB on this and a lot of history. Mine had the same problem. Here you go:

http://dodgeram.info/tsb/2007/21-009-07.htm

 

My sons 06 was doing that and was always hunting for a gear had it at the dealer many times with no resolve until he hauled it back with 3 horses in the trailer, then took the service manager on a ride. the computer was re flashed and now it drives great