What type of plugs did you use?
PO had plats in our 560 which seemed rough to me but i had nothing to compare it to. After reading several plat vs Bosch copper threads here, changed plugs and car smoothed out a ton, especially at warm idle. Fuel mileage improved by about 1 mpg, which translated to about a 6 to 8 week payback.
'02 C230 Kompressor
'89 560 SEL "Frau BlueCar" (retired April 2004)