First suspect on 104 HFM engine is the coil to plug connector/resistors..just change the 3 of them..Definately the most common 104 misfire cause.

http://catalog.worldpac.com/mercedesshop/sophio/quote.jsp?clientid=catalog.mercedesshop&cookieid=21H0MN3YU22N0QBMDI&baseurl=http://catalog.peachparts.com/&partner=mercedesshop&year=1995&product=F1010-84561&application=000357359


Second most common is if someone suckered you into using Plat plugs.