I have a 1994 S350D that has sluggish acceleration about 10 minutes after it's started. It accelerates normally after initial start up but just drops power by 30 to 40% after you get going. It's almost like the turbo stops engaging or at least has about the same lack of power affect. It seems like something gets switched off because nothing else is affected but the acceleration/power.
I've had the fuel tank drained and flushed and all filters replaced, including the screen one in the tank and it had no affect. It doesn't smoke excessively when this happens and no check engine light is ever lit. It seems electrical because when it's shut off for a few minutes it takes off with full power for about the same length of time. I've owned several different Mercedes diesels and none have ever done anything like this before. Hope some of the experienced Mercedes folks here can help lead me in the right direction. Many thanks in advance.