Many times a hunting Idle speed is not caused by the ISC. The ECU can be changing the mixture and timing rapidly cousing the surging.
To check for this, unplug the conector to the ISC while it is surging, you may find it still hunts.
I have two of mine doing this now, a V6 Mighty Max and an Evo III. The truck is more irritating since it drives closer to idle more than the car so it feels like I am jabbing the throttle when driving slow.
It might have somthing to do with the O ring since both of these has had the screw removed and replaced, I thought I put fresh rings on but may not have.

I would say there is nothing wrong with your throttle body itself.