well its kind of like that but not really. The AFM is delivered a fixed, regulated voltage as an input, and it outputs a variable voltage that is proportional to the air flow RATE (volume of air/unit of time). The rate is measured by the degrees of 'opening' of the flap, which in turn wipes the contact, which in turn varies the voltage delivered as an output. So the AFM is an INPUT to the fuel injection system which tells the computer how much air is being sucked into the cylinders, and therefore how much fuel needs to be injected to keep the mixture within reasonable stochiometrics.
If you can imagine an AFM that is 'out of trim' (ie not calibrated) it might tell the computer that at idle, the air going into the manifold (and thus the cylinders) is x. But the true air rate is x-y. Thus, the computer will compensate fuel to the x value, but since the true rate is x-y, it will be rich. The O2 sensor will then measure this, and if its too far out , will flash the CEL for 'sensor out of range' code.
Anywho give it a shake lets see what happens. How much $ is this porsche AFM ? Can you return it if its a no-go (which I dont think is likely at all)
74 GTV with 10548's and Ingram pump
71 Spider 1750 BOMBER ; 1995 LS 78K tight fast car