The fuel pump died on my 93 318is one day while driving on the Highway. I had to have my car towed to an auto shop where the problem was identified as the fuel pump. However, in my case... once the fuel pump died... my car wouldn't start at all.
My MAF died on my 94 325ic as well... my car ran rough and was difficult to keep the it from stalling while at a stop sign. Once I replaced the MAF... car ran great.
Suggestion: Take your BMW to a garage where they can run a diagonsitic for about $100.00. This is probably the quickest way to find the problem without spending too much time and money chasing other possibilities.