Wanted to give you all an update on the situation...
So tonight, I drove up to the airport to meet him. Wheels touched down at 6:20, and by 6:30 we were looking at the car.
The good news: It does NOT appear to be related to my other issue that was fixed by Buckhead.
The bad news: We still don't have a clue what the problem is
I got a clearer story tonight as to what happened at the moment of failure... he said he had made it into the parking area just fine; it was only the last 15 feet (literally in front of the parking spot) that the failure occurred.
Failure "felt" the same as my old misfire problem. But here's the kicker -- no CEL.
I plugged in the DashDaq and tried to pull codes... nothing. 0 pending MILs, 0 DTCs.
Tried to start the car, and it cranks and fires right up -- and settles right into a ~450 RPM idle (lumpy). If you give it, say, 10% throttle... the idle smooths out and you can maintain 1,000 RPM and it will be fairly smooth. Give it ~25% throttle, and it falls on its face. Literally won't go above that RPM.
Engine was cold, hadn't been run in nearly a week so we know it's not a heat issue. Something broke -- a sensor, throttle body maybe? But it won't idle and won't take anything more than 25% throttle.
Conclusion is that he called AAA and had them come to pick him up. He is going to have the car dropped off at Mercedes of Nashville (he knows the lead SA) and hopefully they can plug Star-DAS into it and see what's what.
Still bummed for him... I hate that he only got 110 miles of enjoyment out of it before it gave him an issue. You simply never know.
So, I plan to stay in touch and "guide" him to the right fix (and cheaper parts).
Not going to abandon him and simply say "good luck". Not how I operate.
Cheers,