i recently bought a 1981 240d with a 4 speed manual transmission, and a week or so after i bought it i noticed a weird problem whenever i first started the car each day. didn't matter if it was early in the morning or afternoon, but after shifting through the gears a few times and coming back down to neutral at a stop, the idle would get really shaky and then stall. keep in mind the car would start up fine upon the first turn of the key. there were a few times where i'd be in third gear and it would have a hard time accelerating, rumble a bit, and then just shut off as i was driving, which was unsettling. i switched the fuel filters and air filter and put in some diesel-fuel injector cleaner in the gas tank and the problem went away...that is until a couple days ago i was driving home on the freeway@ approximately 55mph and the car experience the same problem, stalled mid-drive, and i had to coast to the right shoulder. the car is at my mechanic's now and they said they're gonna diagnose the problem and fix it up, but i'm really curious if anyone else has experienced anything similar. thanks

 

Could be filter in the tank getting temporarily clogged up from gunk sloshing around? It really sounds like a vacuum issue though. If your mechanic fixes you up send him my way!

 

thanks joe, turns out the problem was a broken fuel primer pump. the car runs really well now, has a lot more pick up when accelerating