I have a similar pattern of behaviour on my recently acquired 5-speed 300E of the same year as yours. It is intermittent though, and is less of an issue when the car is driven more. It does stall when still warming up sometimes, but that is also not a real problem, just put the clutch back in and it restarts immediately. I have no solution to offer, but will be watching for an answer to your post from someone knowledgeable on the subject so I can check my car out too.
Other than letting you know someone else is in the same boat, I guess this post is kind of useless to you. I hope an answer arrives soon though, and Good Luck (to both of us), Jim
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)