Thanks for the replies!
If it is the engine control, would the load of the tranny be great enough to kill the motor? Seems kind of hard to believe, but the converter is very low stall.
I am able to keep the motor alive by flooring it for a second just before the tranny engages, not 1/2 throttle, not 3/4, but 100% does the trick. A half second after engagement I let off the gas and all is well. I can even switch back to neutral and drive normally after this. Unfortunately, this is my 60yr old mothers car and she won't even attempt to try that. I assume that flooring it pulls the computer out of it's closed-loop mode and is the only reason I can get the fuel I need for that second? If fuel or the computer is the problem, then why does it not stall after I force it to stay alive? That's where I'm thinking tranny....

There are no other problems, no noise, mileage and power are fine etc.
As I predicted, the local MB dealer claimed it was the MAF, but it is not. I still had to pay their $50 diagnostic fee.
The dealer said they have no clue what's wrong and I'm on my own.