I have a 2002 A4 3.0 and I am having problems with the transmition. When I come to a stop with my foot on the break and then go to take off my car revves up and then catches hard giving the whole car a jolt. It feels like it dumps all the pressure in the transmition or goes into neutral. It does not happen when I use the e-break to slow and stop. Is there a sensor that controls this? any suggestions?