I dont what it should be, but I'd expect that there are a few variables that will affect the MAF output, idle speed (volume of air going into the engine), altitude (possibly affecting heat disipation from sensor), ambient air pressure (affecting heat dissipation from sensor), humidity ?
I am no expert and there are others here that will respond in their own time, but it might not be as simple as meauring the output voltage, but then again it might be. Good luck with your problem. Have you tried simply disconnecting the MAF and seeing how the car responds without it? Thats what I did to isolate a MAF issue, cleaned it up with some break cleaner until I received the replacement unit. Good luck.