ive been to my dealer about i dont know anymore but a lot and they keep saying that the problem is normal....they told me it was the torque convertor locking up since i dont know shit about trannys i cant say how valid his statement is. but all i know is that if i were to shift from 5to4 at about 45mph it jerks had and simmalr when its in sport mode there is a jerk right before a stop.