Help!!!
 

I bought a 4l60e from a "no name" company that is supposed to handle 700 horses consistently. I had the guys from GMMG tune my car (new motor), and they are having a hard time getting the tranny to shift properly. I haven't made them get it perfect yet, because I'm about to go from 3.73's to 4.11's (12 bolt), and knew they would have to tune my car again anyway.
Here's what the car is doing. For both the 1-2 shift and the 2-3 shift, at wide open throttle, it seems to open the shift, but never closes it until you get off the throttle. It will act like it wants to shift, then the rpms will smack the limiter, then I get off the throttle and it shifts. They've tried lowering my shift points, and shift timing a couple of times, but no luck.
The guys that built the tranny said they installed several clutch packs and "did some stuff to the valve body". Oh, it doesn't like shifting into overdrive either. It slides into overdrive, and slides right out. Under partial throttle, the 1-2 and 2-3 shifts are very firm.
Could my Vig. 3800 (old) cause these problems? Can the tranny be tuned properly? Will a TransGo shift kit fix these problems? Will a TransGo "Manual" shift kit fix these problems? Anyone ever seen this before? I hate to think I wasted my money and time on this tranny.
Thanks for your input.
Todd