Dont jump in too fast....your car might have a good harness.

Do some VIN research, because I thought the biodegradable wiring harnesses started in 1993.

I have a 1992 300CE with no such issues. The wire sheathing is still pliable after numerous repairs and movement of the harness.

It sounds like you have verified a functioning ignition system and fuel delivery. Have you tried to fire it up with starting fluid into the throttle body? Is there old gas in the tank? Did the car start at all?