Oh, I see. I would shift my attention to the turbo and determine if the wastegate mechanism is working. If it's a pressure actuator, maybe it's stuck open, if it's the later vacuum actuator, maybe it's stuck closed. There are two US 602 models - 1987 190D turbo with pressure actuator and 1990-93 300D 2.5 turbo with vacuum actuator. You might have another car. The 300D 2.5 has a vacuum actuator. To test, rig a line directly from the engine vacuum pump to the wastegate actuator. That should keep the wastegate open while the engine is running. Repeat your ALDA test keeping in mind you engine is unprotected from overboost. Drive the car just enough to confirm the difference you expect. Do not hold the pedal to the floor for more than a few seconds. If there is an improvement, you can either determine why there is no vacuum signal to the wastegate actuator (bad transducer, EDS in limp mode, etc.) or just do what MB should have done in the first place as discussed in this thread - http://www.peachparts.com/shopforum/diesel-discussion/212097-wastegate-actuator-swap-om602-962-a.html

If you have a pressure actuator, temporarily disconnect the pressure signal to the actuator and test as above with the same cautions.

Good luck!

Sixto
87 300D