Update: I spoke with ATS today and they are going to see if a new valve body will fix the issue. The only other thing they mentioned as a possibility is the reverse sprag.
I can't imagine that would affect 1st gear so heavily, but we'll see what happens with the valve body. I have high hopes that the valve body is the answer.
Only thing that sucks is that the labor for a valvebody install is going to be $370+!
I'll update as soon as I get this taken care of!
__________________
'05 2500 4x4 auto - ATS Stage 4 w/co-pilot, Edge Juice w/attitude (HOT flash), Phat shaft 64, cat delete/high flow muffler, custom CAI.