Problems at Idle

[Au2falcons]

Hi guys, got a minor niggle with the AU which I hope someone might have some suggestions about.

When the car is at operating temperature in drive/reverse (auto) idle speed is about 650rpm. Idle is smooth but when I turn on the AC or turn the wheel (when it's not rolling) the revs drop. This is normal and the ISC will compensate to raise the revs, but it's slow to react and the revs drop down to about 400rpm and naturally the car starts to shake. Within about 2-3 seconds the ISC compensates and the revs come back up. It's quite annoying and I don't thing it should take that long for the revs to compensate.

Here's the stats;

-Car has done 95,000 clicks
-Has new Air filter, fuel filter.
-Just cleaned the throttle body (which was dirty)

I've pulled the ISC off and there is a light carbon residue inside but nothing major.

Do you think the ISC is sticking? Any suggestions?