bp,
try running a bottle of tecrolene(?) sold by chevron throught it. try it for every other tank for 4 fill-ups and see if it helps. most city cars suffer from carbon build up on the intake valves wich can cause hard cold start and rough idle conditions. other "fuel system" cleaners claim to work, but tecrolene seems to work the best, but it takes time to work. i have used it in my 190e and have cleared up a hard cold start problem as well as low idle. just my .02 worth but hope it helps.
Joe