Since I now have three MAFs, I decided to test them to see what sort of signal they put out. To create flow through the MAF, I put it up against an ordinary box fan, and ran it on low and high speed.

Here's the pinout on the connector:

rounded end ( 1 2 3 4 5 | flat end

1 - IAT (temperature)
2 - 12 VDC
3 - ground
4 - 5 VDC
5 - MAF signal

Results:

rate pin 5 - MAF
no flow 1.0 to 1.1 VDC
lo 2.0 to 2.1 VDC
hi 2.2 to 2.3 VDC

All three made the same signal.