01 LB7 168,000 on what i believe is a stock tranny. Now when im going around 33mph the truck will not shift unless i left off the throttle at just the right moment. If i miss the shift the dash lights come on and it throws a code and it throws it in limp mode. Once i get it to shift it does just fine..my question is the tranny done for? anything i can do to help prolong its life? lol not ready to break the bank yet!