toddo,

The key switch is a good lead. My daughter's car seems to do that voltmeter twitch too. I will check it out. Her car runs fine, especially after replacing the cap, rotor, and wires and used to have a similar surging problem at various rpm and load combinations.

I imported a bunch of 230E model W123 cars in the early 1980's, all of which have proven to suffer from "fuel pump relay fading syndrome." It may be the weather here compared to the Fatherland, or something else associated with adding an emissions control system. Later model replacement relays seem to be a little more robust though and I am no longer having to stock these items for relatives who jumped on the grey market bandwagon when they found out they could get a new MB in 1984 for $12,000, very nicely equipped (the federalization was another $3K to $5K). When the pump relay fails on a 230E though, the car does not run at all, momentarily anyway. It may start again after being off for a while (cooling down?), but it will fail again a few days later. The pattern repeats with time running between failures getting shorter and shorter. My Aunt has 3 relays, one installed and two "bad" ones in the glove box. When it happens to her now, she just changes it out, and runs on the "bad" one. If it happens again, I get a call and send her a replacement while she plays musical relays and gets by.

I will check into the ignition switch - thanks for the lead. Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)