I?m having some trouble with my 96 c220d van
In 4th and 5th gear at 1800 to 2000 rpm the engine seams to have a lack of
power, it "shakes". Help me?

There's very little knowledge on this site about MB vans. In fact, I think there is very little knowledge on the internet about MB vans. Try benzworld.org. There's a discussion devoted to vans and trucks there, but very few posters. There's a Sprinter group at Yahoo, but not much mechanical knowledge on it in my opinion.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13