DME Idle Speed Stabilizer
 

Well, since the car seems to not want to return to idle with the A/C on, and sometimes with it off, I began to poke around. The microswitch on the linkage works, and the idle speed motor hums, but with the hose off, all the impeller thingie does is bomve back and forth about an eighth of a turn. Took it apart, and there is a major divot on the "commutator" of the motor. Put it back together.

I assume this is some sort of an air pump and should spin? Does anyone know for sure?

Greg,
No, its not a pump. Its a valve, which meters idle bypass air under control of the DME. The basic plan is that the DME drives the valve to achieve the target idle RPM set in the chip for your car. The stock chip for your 85 has 800 RPM idle target. Later Carreras have 880 RPM target idle.