Ok. I have a fairly good understanding of R/C's in general and know my RC10GT like the back of my hand. This new problem though has me stumped!

heres the problem/symptoms:

Well I just got through breaking my truck in. It has the CR brake system (like in a nitro hawk w/leather strap pulling over a bell over the slipper assembly) and it works great. The truck has a brand new robinson racing tranny and all new innerds. The engine runs like a top but it doesnt get much pwoer to the ground. The clutch nut is as tight as all get out (over 80ft. lbs of torque on the torque wrench) and the cltuch is working properly with stock cut shoes. The slipper is fully locked right now to try and pinpoint this problem so thats not it. I am thinking its the rear diff gear. I think the spring might be loose. Here was the problems i was experincing:

-Acceleration was horrible. Had to feather it a bunch to get it to actually move and really revved it out.
-couldnt climb any real grade or cover any rough terrain like grass. Ashphalt only.
-top end was around 15mph with engine screaming.
-the slipper was locked up so it wasnt slipping at all.
-the engine is fine, i used it in a old RTR i had and it screamed and threw it around like nuttin.

Is my ball diff spring too loose?