try running some techron through it for a couple of weeks. put in a bottle per tanka nd do it a couple of times, see if that helps, it could just be a slightly clogged injector.
Otherwise have your plugs check and air/fuel mixture checked if it can be adjusted.
Your cap and rotor might be worn too, how many miles ont he car?
For a good mechanic recommendation, check the good mb shops forum. I think Steve brotherton is in florida, but not sure how close he is to miami.
'92 300CE - Sold
2004 C240 - C7 Wheels
2015 ML350 - P1, Pano, Ash poplar wood, Sport Dinamica interior, Running Boards Keyless go.