Don't forget about the possibility of bad connections and grounds, especially on the various position sensors. I had a similar problem on my 535i, and by pulling off all of the connectors (sensors, throttle, airflow meter, and idle control valve) and spraying with Deoxit d-5 (a corrosion prevention spray (www.caig.com)) The problem went away completely. That was about 30,000 miles ago.

You might want to check the grounds as well, make sure they're tight and corrosion free.

Good Luck!

I was driving on the freeway at 75 and all of a sudden the car starts to loose a great deal of power. Then it comes back. This problem has been getting progressivally worse until one night it was stalling over and over again. Finally it was running (barely) and I took it home. Next morning I took it to a Bosch specialist and the car was running good again. So I figured maybe bad gas or water in the line. I fill with 93 octane and some water remover and it went away for about a day and a half. Last night the problem came back and is getting worse. I'm tired of driving by the shoulder worried that the car can stall at any moment and have to tow it. PLEASE HELP. PS fuel pressure regulator was replaces last Oct.

THANK YOU
Sari
86 535i