Since, as phunk said, it is unlikely that both MAFs went out at the same time, I'm still leaning toward a high resistance somewhere in the wiring common to both MAFs.
You said you had 12 and 5 V at the MAF harness connectors but that was at no (electrical) load. To check for high resistance between source and sensor, you need to check V when the MAF is operating.
But it's possible that they went bad together. With all the other problems you are having, it wouldn't surprise me if they all have a common cause, ie, wreck, water damage, etc. I'd see if I could find someone that would loan me (or sell cheap) a known good, used MAF and see what it reads before buying a set. If the same MAF is used in other, more popular Nissans, it will help your search. CourtesyParts.com has a good parts look up for 370Z - look and see if they have some kind of cross-reference for part numbers.
Edit: Or you could have a problem totally unrelated to the MAFs. Lots of weird things going on with your car.
