Try reposting this in "Diesel Discussion". I can give you a few suggestions though:

1. Check all vacuum lines under the hood, make sure they aren't clogged and or broken.

2. See that 5 way vaccum fitting at the front of the engine? Replace it with a 3 way - which disables all the stuff on the passenger side of the engine compartment.

3. Make sure the turbo spins freely and is generating the right amount of boost.

4. The device you mention is the ALDA - it is under the intake manifold and sits on top of the injection pump. Make sure the plastic lines going to it are not leaking (and also that the unit itself holds some vacuum).

Lastly, this car is FAST for a diesel. It should blow away any of the older Mercedes diesels, especially that 1981 300D!