740 stalling problems
 

I have a 1985 740 GLE. The other day it totally lost power for a couple of seconds, but as I pumped the accelerator, it came back to life. A few hours later it died on me while I was on the freeway. It would idle, then, but whenever I pressed the gas the tachometer would drop and it would almost stall. Soon it couldn't even idle.

I had it towed to a shop, and it sat there over night. They started it and it idled fine the next day. They said it had a few problems at first, but in the past day they haven't seen it so much as sputter. And they can't find anything wrong with it.

Does anyone have any ideas what this might be?