i have a 1990 pontiac grand prix le.3.1 fuel injected. i've changed all of the sensors in it. put a new comp. in it. put all new gaskets on it, went and bought aa code scanner for it. the code scanner keeps telling me it's the maf sensor.but i can't seem to find the maf sensor on it. i found the map sensor replaced it 3 times already. i just put it all back together and it's doing the same thing.not wanting to stay running. when it is running. i press on the brake to put it in gear it dies. and has 2 be jump started. then the service engine light comes on. and the it just dies as soon as the service light comes on?