Has your engine wiring harness been replaced? I have the same vehicle with about the same mileage (94 E320, 180K miles) I chased lots of intermittant problems, fault codes, ,CEL, idle surges........After replacing the wiring harness I was able to diagnose/correct the few remaining faults. If your wiring harness is original, I can almost guarantee it is causing you problems. When you completed the work you described, you probably disrupted the wiring harness enough to crumble what was left of the insulation allowing shorts through out the system.

Hope this helps.