So i just bought this truck last week its an 06 CC silverado 5.3, theres 250000 kilometers on it but it works perfect with stock programing, but if i put the performance tune from a superchips programmer the transmission seems to slip pretty bad from 1 to 2.....I used this on my last truck an 04 and it loved it shifted nice and hard....Is the tranny just wore out or is there something else i can do??????