I think the 1995 was the last of the years with the self destructing wire harnesses:

Rough RUnning C280 Wiring Harness - MBWorld.org Forums

I only think of this because you have two simultaneous but seemingly unrelated problems which could both be electrical. Similarly it could involve a bad ground somewhere. I realize these are not very specific ideas but if a ground goes bad then everything goes out the window so to speak. For starters take a look at the wire harness conductors and see if any are cracking or turning to powder.

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra