This seems to be a common problem among MBs, especially CIS cars. There can be a number of things from rusty fuel lines, to injectors to vacuum problems and the list goes on. Go to the Search button on this site (little blue buttons above) and type in rough idle and I bet you will get tons of answers!!! Good luck.
'86 420SE Euro
904 Midnight Blue, Gray Velour
Dad bought it new, now I own it.
"A Mercedes-Benz is like a fine wine, it only gets better with age."