My '87 325e (240,000 miles with 150,000 on factory rebuilt engine) died at highway speed as if I had turned off the ignition switch. About a week later, it started happening with increasing frequency at all speeds, especially when trying to accelerate from a stop or maintaining speed going up a hill. This is very erratic, as I may drive around town for ten miles with no problem, then the next time it may die every 200 feet. I can restart most of the time by depressing the clutch, turning the ignition switch off then back on, and popping the clutch. It will not restart unless the ignition switch is turned off- just popping the clutch won't do it. I replaced the large air intake boot- no effect. I and a local mechanic have checked for other vacuum leaks without finding any. Any ideas????? Please help. Thanks!! Travis