[Outback Porsche]

Well, bugger me! It's not supposed to work? Hmmmmmm!

Did it run like crap when it did start?

In the early AFM's the resistors are set up so that the voltage output is an exponential relationship to the opening of the barn door. In the new AFM it's a linear relationship. The fuel/timing lookup in the DME should be all wrong?

I wouldn't advise swapping parts in and out between the AFM's. I would suspect that they are designed very specific to each model.

Test the ignition system using your friends DME, if it works you know what the fault is. If it doesn't, the go down the path of the O2 sensor (or do the O2 thing first - it doesn't really matter).

Ultimately though, your half way towards an upgraded engine control system. I'd find myself a newer DME anyway.

If you do the later DME you'll need to get the later AAV or cold starts will be a problem.

Cheers,