And the answer is.....................
You guessed it.........the wiring harness. After considerable consternation, parts substitution, wacky readings and other associated grief; the sun, moon and planets aligned to give us a break.
After about 1000 miles, the car did it again.
I'm really getting to know the local float driver for the dealership.
Once we arrived at the shop and moved the car (ran normally at this point again) hooked the car to the diagnostics.....no fault codes.....values normal.
Ran the car for about 20 minutes on the highway, returned to the dealership (car was symptomatic) and hooked diagnostics again while the car was running. Actual values for the LH1SFI was 1.2v and 1.8v for LH2SFI (MAF readings). First time we had seen this.
Swapped MAF's side to side....still the same, swapped ECU's.... still the same.
AT that point the razor came out and all the sheathing, tape, and whatever from the wire harness between computer box and the LH2SFI MAF came off (except for about 1" at the connector to the MAF). Nothing. Grounds were rechecked. Nothing.
For whatever reason, the tech looked inside the remaining 1" of sheath at the MAF connector.....Bingo! Bare wires. Right at the connector's hard case.
Other than the 1" or less at the MAF connector, the rest of the harness looks new. Every other spot that had been checked, the wires were pliable with no signs of hardening or brittleness.
Mike (myarmar), thanks for the part number for the replacement harness. I don't know if it has been updated, but the number that they are using (here anyways) is 140 540 00 36. According to the instructions that are associated with this repair kit, the harness is cut and repaired in the cable tray, rather than in the computer box.
Thanks to all for the suggestions and support. I know that in the shop, as well as for myself, that there is a certain sense of relief for finding something tangible that could account for all this grief.
A mercedes is an inanimate object and therefore must respond to logic and reason.