Me and a freind just installed the main and 4th gear billet servos in my 04 ss awd.problem is it is not shifting into 4th gear.i feel it shift 2,3 but i can run down the interstate 3200rpm at around 70mph and that seems like there should be another gear but nothing. i even went up to 4000 rpm and it just stayed in that gear someone help is this normal or something wrong????????