Did you check the MAF wiring end to end? i.e check for continuity from MAF plug to termination at ECU. I had similar problem when one the wire form MAF sensor was broken near ECU.

You can find the wiring diagram here http://www.autolib.diakom.ru/CAR/Mercedes-Benz/1995/C220/SYSTEM%20WIRING%20DIAGRAMS/5301.pdf

P.S: C220 uses same engine as E220.

If you are comfortable with rigging your own interface try,
http://www.peachparts.com/shopforum/showthread.php?t=236925&highlight=HFM+scanner

You can monitor all parameters that DAS can.