I have a 1990 ford mustang GT 5.0 V8. today it started good until after school, it would fire and ignite, and then boom. it died. a couple of failed trys and it started and ran. but when i turned it off it was buzzing in the back, of the car, below my hatchback trunk thingee. it buzzed for about a minute and stopped. when the car is on it buzzes but it always stops when you turn it off. what the hell is going on?