I'd build the code reader as suggested above.

I've never know an O2 sensor to cause a surging, though.

The usual culprits are, not in any particular order;

1. MAF sensor
2. Throttle Acuator (what you are calling the throttle body).
3. vacum leak

You mentioned that you cleand the throttle actuator, but cleaning is generally not effective. These actuators have defective wiring harnesses that also fail (and can't be fixed), as well as having potentiometers that wear out / fail over time.

Arthur Dalton has been particularly helpful with owners of these cars. Try doing a search for his posts and your problem, and I'm sure you'll find a ton of info to look at.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".