Now we're getting somewhere!
Ok, thanks to everyones help, and countless posts...I am very close to fixing this thing. I think this vacuum pump has gone bad. I took it apart, and it doesnt look that great inside...so, now, I tried to find the part (202 800 12 48) here on the parts shop, but they dont have it....does anyone know where I can get one...and cheap if possible...perhaps a used one? Thanks in advance.
1998 ML 320
1994 Blue C220
Im going to Grad School @ the University of Iowa