e24 problems

[chooker]

Okay, you will have to hate me for asking this, but what causes a car (1979 633csi) to go from working perfectly one minute, to almost nothing? Its okay while its cold, but then sounds like its not getting enough air (runs as if its missing) unless its revved to about 3000 mark. While revving or normal running it backfires (nothing major, just little pops and cracks now and then). Spoken to a mechanic (beemer specialist) who said it was the airflow meter and to tap on it with the handle of a screw driver while its running. Nothing happened. It's not blowing any smoke, or using any water or oil, but smells as if its running rich. Spark plugs were gunked up (only 2 months after car received full inspection from above beemer specialist, Quandt Motors). The only reason why i'm asking you is because i'm a tafe and uni student, and am not sure how serious this is (ofcourse its serious enough to stop me from driving it out of fear of making it worse). Any suggestions? Anything I can do myself?

thanks