E420 harness and shifting
 

Hello,
I just got a "good" running and "good" driving 95 E420.
Now that it's home and not being driven in the snow... Turns out that it idles high, up shifts into 4th by 30 mph. Refuses to downshift and/or kick down. Seems like a snail compared to my 92 400E.

So I figure the ETA needs rewired. Shows an open between the main motor. However, upon closer inspection... The entire engine harness is trash! I'm not sure how the car even runs in this condition.

So my question is, would a bad engine harness cause the symptoms I describe? Or is the ETA also likely bad? I cut into the ETA harness and the wires are fine, but obviously could not get really far down into the harness with it still installed.

Any ideas?

Mercedes M104 ETA throttle body bad wiring symptoms. - YouTube

For a M104 E320. Maybe some similarities?