"ASR" It's an electronically controlled limited slip differential for controlling it when one wheel loses traction. There's an idiot light labeled "ASR" in the instrument cluster on the right side.

I just went down the "throttle actuator" road on my 94 e320 and had 4Mercedes rebuild mine. I hate to be the bearer of bad news, but in addition to the bad insulation, there's also a potentiometer inside that goes bad and usually has to be replaced. That's why rebuilds have to be done by someone like 4Mercedes or Bechmann Technologies. Maybe you'll be lucky and not need the pot.

These articles regard a V-12, but they apply to yours as well

http://v12uberalles.com/throttle_actuator_rewire.htm

and

http://pages.prodigy.net/jforgione/MB_asr.html

Good luck
Bob