I have a problem with my connector to my map sensor. I have a 89 formula with a 350 tbi in it. When the map sensor is disconnected the car idles smooth but does not run when put in reverse unless I gun it. If the map sensor is plugged in the car shuts off. I put a new map sensor in and it does the same thing. Do I have an electrical problem or ground and if so what do I look out for?