after about 20mins of driving, the gear changing became really rough, with steady throttle (low speed 20-40km/h), it feels like the rear dif bumps on my back or like the tranny straggle to change gear.... almost feel the same as with wrong size of tires and it's messing with the awd system. It only happens when driving slow and on flat road (which means when giving it more throttle, or driving it up/down hill, everything become normal) ... anyone have similar experience? any advice would be nice... thankx..