A *great* MB mechanic and $500 resolved the problem. The computer wouldn't produce codes, though the CHECK ENGINE was coming on, and the power loss occured just after a hard deceleration.

Turns out the OVP relay malfunctioned during the
deceleration, and the engine idle wasn't being done properly. Also after turning off, then on the engine, the CHECK ENGINE came on for a minute.

Though the computer couldnt send out codes, it knew that the O2 sensor was bad (crudded up w/ 60K miles on it...definitely time to replace.) So, with OVP and O2 replaced, and Lambda adjusted, alles is gut ins MB-auto Deutschland!