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1985 Mercedes Benz 300d Product Categories - Peachparts
First item is the usual culprit for a shaky engine, once warmed up.
Second is the new style primer pump.
Your ALDA may need adjustment. Is there a black cap on the top?
If so, it hasn't been touched.
If not, it has been adjusted.
Turn the screw CCW a half turn after loosening the lock nut. Try accelerating then.