Gilly, csnow et al.:

Here's the denouement. Part of the problem is that this dealer puts a service manager in between the
customer and the mechanic. It was the service manager who was harried and not very good who was
confused about the steering angle sensor and the number of oxygen sensors. It turns out, however, that
the mechanic was not that hot either. But at least he was honest.

to recap:

1. Monday an authorized Mercedes dealer/repair shop picked up the car.
2. Tuesday the service manager told me our stalling problem was the "steering angle sensor".
3. When I insisted on talking to the mechanic, the mechanic said it was the crank angle sensor.
(Despite replies to my thread, he insists it is a crank angle sensor, not a TDC. He says it fires the
plugs, so it is not just a TDC sensor.)
4. The mechanic and I agree that he will replace the crank angle sensor, the OVP, check the vacuum
hoses, and clean the idle control valve.
5. Wednesday the service manager calls and tells me the car runs rough on the road and the mechanic
wants to swap out the oxygen sensor. We replaced the oxygen sensor two years ago, so I insist on
talking to the mechanic again.
6. When I finally reach the mechanic, he says that in fact the car runs well, the service manager
didn't get the right message, but the idle is low and rough.
He says that he recommends the oxygen sensor because no signal is coming from it. I repeated to him
that the oxgen sensor was replaced two years ago and is unlikely to be bad.
7. The mechanic calls me on Thursday to report that he checked the actual output of the sensor and
found that indeed it works (!) but that the computer is not using the information. He says that the next
step woudl be replacement of the computer.
8. The mechanic replaced a resistor somewhere that caused the idle to rise from 500 to 700 and
told me to see if that helps because the computer costs about 1200 bucks.

Conclusion: This dealer did about a kilobuck of useless work.

Anybody know where I can get a good used computer? part KEInjector Control 0085451632?
I won't print a verbalization of my feelings about his whole process, I will leave them to your imagination.

Conclusion: This was a frustrating experience.