Does anyone have a used air mass flow meter that would work on a 1980 spider (FI)? Or recommend a source?

Try Vick's Fiat catalog. Part number 33-1385, I believe. Check to be sure. It runs around 600$

ha ha ha... here's a better suggestion... find another forum where guys are routinely parting out Fiat Spiders, and buy a used unit from one of them.

give this forum a try:
www.fiatspider.com

Spiders are parted out routinely at that site.

Mikes right. fiatspider.com. Think Maytag has one for sale. Parting a 80 fi out I think

The other place I've used... Auto Italia in Windsor CA

have one if you still need it