Mario,

Thanks for the response. Did you mean pin 3 of X11 on the fender or pin 3 of X11/4 on the firewall?

I checked the thread on the MAS pot. Good info, but it seems that's a suspect when there's idle surge or fluctuating idle. I don't have any of those symptoms. Engine shakes but tach reads steady at idle. No hunting.

Sixto
95 S420
91 300SE
87 300SDL
83 300SD