Is the entire wiring in a mid 90s W124 biodegradable?
 

I remember reading that my wiring harness was replaced but is the wiring all bad in it's entirety? If the car is going limp where do I look?

All I have ever heard is the engine harness being a problem.

This was discussed in the past here, all of the wiring is likely to be bio insulation. The under hood stuff suffers first due to heat.

There have been reports of dash fires due to deteriorated insulation. It would be a real good idea to find power distribution points and add Maxi fuses or fusable links.

What could cause it to go limp?

Underhood wiring could be a cause but some basic testing is needed. What are the trouble codes and what do you consider limp?

Do a search as my understandings is that there were two (2) harnesses that were bad in the years 92 to 95 if memory serves...