We're still working on this car.

Agreeing with AMG, the "throttle surging" is probably actually the "cutoff" that we experience when attempting to accelerate. It feels like throttle surging when the power comes on and off rapidly. The limp-mode cuts power at 1500 rpm and then allows power again at about 1200, so, with your foot on the gas, it bucks around on and off and feels like surging.

We've done a lot of other research. We're thinking it's the Throttle actuator and the throttle actuator wiring harness. Harness is ordered from Germany (about $100)

We're going to send the unit to Beckman. They will test the Actuator for $80... which they will apply to rebuild cost if it's bad. (rebuild is about $1000 compared to a new MB unit at $2000+)

Incidently, mine occurred several times on 90 degree days, but happened most recently when it was only 75 outside. Raised the hood for 5 minutes, and it started right up again -- no problem.