I have a 2002 Monte SS and all of a sudden be driving down the road and my speedometer would drop to zero then back to the speed that I was going. When I let off the gas pedal completly is when it happens mostly. It feels like the car is lurching when this happens. Does anyone out there have any ideas? My tach drops when this happens. Tried throwing car in nuetral to see if car stales or dies and car runs fine. Thanks.