[drone]

The logic of it is, imho, between the throttle activator and throttle there will always be some small clearances that manifest themselves as "slop" for want of a better word.
On my V40 there are several feeds into the inlet tract between the filter and throttle, one of which comes from the cylinder head (mine is the Mitsubishi engine btw) inevitably some oil vapour will find its way into the manifold, as it is meant to. The throttle butterfly will be cooler than this oil vapour and it will probably condense into water, soot and maybe some oil all in minute quantities.
With the throttle at idle the gas speed through the throttle/butterfly interface will be at its highest as the space on the engine side of the butterfly is at nearly a full vacuum and the air on the otherside, the filter side, is at one atmosphere, approx 14.7 psi. Small amounts of contaminants will be too (relatively) heavy to transit the tiny gap and will be deposited, either on the butterfly valve or on the throttle body and will over time build up. We're not talking much here, this build up will act as a brake on the butterfly and the aforementioned slop in the system will prevent the butterfly from opening immediately the aircon compressor loads up the engine so the revs drop and the ecu opens the throttle more and it pops off the crud. The engine speed drops below 500 rpm then suddenly rises to 900 or more rpm (or thereabouts)when the ecu shuts the throttle again, the dirtier the area is the more this effect will be noted.
You and I cleaned the crap off and the throttle no longer sticks, ergo no hunting.
Please note this is just my theory, may well be wrong but nearly a 1000 miles have been added to my example since I cleaned it and it is not a problem anymore.
It worked for us both and I hope you understand my version of the logic involved.
I'm also glad it worked for you