First of all I have an '03 3.0 Quattro, Automatic, 90K. When the car is at a stop (traffic light, etc.) I feel a "jolt" through out the car almost as if the RPMs drop slightly immediately rebound to normal, but the tac doesn't seem to move. I have noticed this problem is worse when the ambient temperature is 65 F or below, or when it is warm enough to have the a/c on (>75 or 80 F). Any suggestions?