Phantom wire 400E????
 

There is a wire that comes down from up top, on the drivers side down splits and one goes up under and plugs in under the motor mount, the other one runs along the back of the oil pan and up the other side and plugs under the other motor mount???? The reason I ask is it is in very bad shape

Its part of the lower wiring harness, just search the forums here and on benzworld. It serves oil level sensor, oil pressure sensor, alternator, and starter. Lots of threads on how to make your own or buy new.

Good luck (btw i havent replaced/repaired mine either)

There is a black wire that I saw running along the back side of the oil pan and it was not part of the lower wiring harness (I just changed my harness). The wire was in good shape so I left it alone. I am curious to find out what it is, though. Maybe for the O2 sensor?

Not O2 sensor..

How about the knock sensor under the engine mount.