before my 1988 528E would idle very low and the engine would rattle, like i could feel it vibrating. i was going to have it checked on soon, but today after parking my car on an incline (does it make a difference?), i tried to start it up and no luck. wait a lil bit and try again as i usually have to try two times to fire her up and no luck. wiated some more, still no luck. what do you guys think it could be? it is quite violent, ill turn the key and it will rattle very hard and it will refuse to start up. what are some possibilities? if i have it repaired how much do you think i am looking at?