Brought my car to an independent shop (finally found a great shop after beeing f***ed by the dealer for 5 years).
He diagnosed the Mass Airflow Sensor to be bad and the throttle actuator to indicate open throttle.
All was changed, car purrs like a cat.
'07 ML320 CDI (398 ft lbs / 1400 RPM)
'91 928 GT Supercharged