Check the coil. I had a similar problem with my 1992 300TE 4Matic Wagon, (which I recently sold). It would start and drive fine, sometimes for a week at a time, and then all of a sudden, especially if it had been sitting for more than a day or two, it would run rough and stall. Sometimes it would re-start right up, other times not. It finally stalled at an intersection and would not re-start so I had to have it towed to my mechanic. When a fuel test and others came up negative, he diagnosed it as a bad coil. $325 in parts and labor later, the car started and ran beautifully. Then I sold it before anything else could go wrong! Good luck.

1962 MB 220SEb "Fintail" Sedan, 196,000
1992 MB 300TE 4Matic Wagon, 150,200 (sold)