Switches sometimes start going bad, its not always they just fail. Not talking about the little switch by the shifter under the plug, there should be a switch somewhere on the transmission I believe(Bill will correct me if I am mistaken again). The car has to go thru neutral to get to reverse, so it is a possibility. Could be the pump also, I would at least check the fluid. If the car had a low idle already I could see that as a possible culprit.