Check all connector seals.
There was a recent issue where another member changed the mass air meter, and the seal was pushed into the connecting pins.

Did you replace all of the engine compartment wire harnesses or only one?
MB Wiring Harness Failure
http://www.peachparts.com/shopforum/showthread.php?p=927185




Have a great day.

__________________
ASE Master Mechanic

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D

https://www.boldegoist.com/