hey man, don't mean to harp on this cleaning, but did you open the butterfly & clean about an inch into the opening? usually a ridge of deposits builds up there, also on the butterfly itself, it can build up a ridge on the edges... you need to clean the inner edges of the butterfly too... the face of the butterfly shown in this pictures has no bearing on the function hear, it's the inner edges that really need to be cleaned, incase I didn't make that clear enough.
the throttle opening at idle is very small, it doesn't take much to build up enough edge to reduce that flow...
usually if the problem is something else it would show a fault as a CE light, if you're sure it's cleaned well on the inside too then it needs a proper diagnosis I would say, but I would double check the buildup before giving up, unless you know you did it well enough...