Problem came back after about 40 miles. I was on my way to work, and it occurred gradually, took about 1 to 2 miles to fully come back. Disconnected battery and reset computer again when I got to work; afterwards it was gone again. 40 miles later, it is back once more. So I think the adaptation interval is somewhere around 40 miles (to answer my own question).

It would appear, then, that cleaning my MAF didn't fix the problem. Evidently, resetting the computer restored adaptations to baseline which made it appear that the problem was resolved, only to return in 40 miles when the computer reached the limits of its adjustment. But I believe david s poole is correct, that I still need to replace it. Why? Well, in my research I stumbled upon this VERY HELPFUL document which outlines exactly how to test a MAF. No more guessing - it is a very exact procedure: http://www.x-desk.net/ximages/21302_pgsi0079en.pdf

The output voltage of a healthy MAF is supposed to be around 1.00 plus or minus 02 with key on engine off. Upon starting the engine, it should rise to 1.6 and then travel all the way to between 3.8 and 4.4 at full throttle.

When I tested mine, the output voltage was 1.462 with key on engine off, which is way high. When I blew a little bit into the MAF, the voltage would go both up and down (it should only go up) and was very erratic. Upon starting the engine, it was at 1.64 (a tad bit high). I didn't bother with the full-throttle test, as it was very evident to me that the MAF was malfunctioning.

At least I think I know what's going on now. The car is still driveable, you just can't accelerate slowly. Have to give it lots of throttle from a standstill or it will go flat. I will be ordering a new MAF as soon as I can.

Oh, and the document also settles the debate over whether or not there is actually a difference between the $130 MBZ element and the $59 generic (VW, Ford, Audi, etc.) element. Definitely different part numbers, so I wouldn't even mess with the generic since I like my catalytic converter the way it is.

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08 W251 R350
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91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
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75 W114 280