I have a 1996 2500 4x4, V10 auto, it has been sitting for 2 years because of the cursed death wobble. I have gotten around to getting it going again. I have invested in a Dick Cepek lift kit and in getting ready to install it I drove the truck a few miles to my shop. I have been starting this truck on a regular basis but haven't driven it much. On the trip to the shop it wanted to take off in drive, would not take off in 1st. However it works fine if manually shifted through the gears. All the speeds feel good, no slipping or noises, it just won't shift on it's own. I did have the trans rebuilt 5 years ago and it worked fine when I parked it. Any ideas? Waht should I check first?

 

Whats worth a try is, since it has been sitting, I would suggest a trans flush, check the fluid and after you put new in, drive it then and see how it feels.