Check ur fuel filter
Dude, i have a 84 318i. I just bought it after it was in the same place for a few years. So, the gas tank is full of crap. Until i can take it out whole and have it steamed, i have to check my gas filter every week. I'd say check your gas filter and you might also want to check the fuel pump inside the gas tank. Just pull your rear seat up, unscrew the metal lid off and proceed to take the gas pump off. Sometimes they also get full of crap.