99 986 2.5 - Idle air control valve not working right?

[mach_y]

I am really hoping someone can help. Engine runs rough under about 2500-3000 rpm. I can see / smell exhaust, definitely seems to be running rich. I believe this is due to my idle air control valve (IACV) not opening.
My IACV buzzes loudly when the key is in the ACC position, but does not open:
IACV buzzing

I also used my durametric to run the IACV test, and it buzzes loudly and then quieter, but I don't know what that means.
IACV testing

I have bought 2 new IACV valves so far (both generic). However, the same exact thing happens with my original bosch IACV and the two new generic ones. My best guess is that the signal going to the valve is not good, but I don't know where to look / troubleshoot from here.

Any ideas on what to check next would be greatly appreciated. Thanks!