I have a 1988 mustang with a carburated 302. Pretty much stock. I went to the gas station last week filled up with gas and the car wouldn't start. No cranking no nothing. tow it home and i figured out that im getting no spark. I get power to my msd but nothing coming out. How often do msd boxes go bad. I bought the car with the msd on it so i don't know how old it is.