Air-Flow meter interchangability

[Chief]

I have a Fiat Spider 2000 project car with L-jet (air-flap type meter and O2
sensor) and I believe the air meter is bad.  Voltage deflects normally about
half way open then goes kind of haywire.  Shouldn't the voltage deflect
mostly linearly all the way to full deflection.  The car idles, then revs up
to when the air flow meter hits a certain spot, then sputters back to idle.
I can only get the thing to rev to around 2500 rpm or so.

Is this something that could be fixed or should I get another from the
j-yard.  To what degree are air flow meters interchangable between different
brands of cars that have L-jet systems.  Fiats are really hard to come by
these days.

Thanks.

Ed Hilker aka "Chief"
'84 SS w/700-R4