Engine will not stay on....Can anyone help??

[explore]

HI, i'm new to this. My wife has '81 320i. For some reason lately whe we start the engine it will not stay on, unless you press accelerator all the way, and even than idle jumps up and down. When you put it in to the gear and try to drive it...it stalls. Friend of mine try to look and said that he can hear a vacuum leak noise in the engine compartment......
Does anyone know what the problem might be and where I should even look for the vacuum leak, if that what it is?
Any help will be much appreciated.

[Aether]

If it's not the vacuum leak, which I guess you'd find in the vacuum hose, you may just need to clean your injectors / spark plugs or replace them.

['85 318i]

yep, vacuum leak or plugs/injectors. change the plugs anyway... it can do noithing but good.

[explore]

ok, where do I look for a vacuum leak..... I don't know anything about BMW engines. I removed the air filter assembly so it's out of the way. But how do I go about finding where the vacuum leak is? What am I looking for?