wonky idle

After drivin the car and lettin her cool down it idles a#se ways for a few minutes and, then ticks over fine .Any one got idea why it does this

I get the same sometimes with my yoke, say I drive home from work and shut it down, car cools down. Then I realise I forgot to pick up milk and bread, half an hour later start it up and it idles at a very low speed, almost cutting out with a kind of a rattle from the rear left (exhaust area) then it sorts itself out after about 30 secs. I was really worried when it happened first but now I'm used to it and don't think anything of it. I think some cars have an idle air control valve that bypasses the shut throttle butterfly to allow enough air in to let the motor idle. Sometimes they get gunked up and need to be cleaned, not sure whether this arrangement is used on Subarus though.

ive seen some stuff wrote up on cleaning that valve all right might be worth looking into all right cheers man