Update: Still rough; now Code 2 Oxygen sensor?
Update: I replaced the plug wires and connectors (But I did not test the new parts or the other two old condensors). I drove it about 10 miles. The idle is still rough but different. Before the new wires it missed very regularly--at least once per cycle. Now it starts right up and seems to idle perfectly, but then stumbles about every second. When I put it in R or D it gets much worse, stumbling erratically. It had very poor acceleration up to 3500 rpms. It pulled fine going slowly up our steep driveway. The check engine light stayed off, but when I pulled the general codes I got Code 2 (Oxygen sensor?). There were no detailed codes for pins 8 and 14. I will order a new sensor.
By the way, MB shop records indicate Code 7-8 and a new Air intake sensor April 2001 at 89k--six months before we bought the car.
Thanks again for all the help!