Geist, I'm thinking (uh oh, here's trouble!) that your problem is different that Krazyc's problem. He doesn't have stable idle on the ground, rather, it will "hang a long time on high idle" then will suddenly drop 300+ rpm. OTOH, your idle on the ground was "very consistant without any changes" but that you had a higher than desired idle on landing approach until the speed dropped. Two different issues.

That's why I suggest that Krazyc might have a mixture problem. He did state that when he richened the mixture there was a point the idle improved but that he had transition issues, so he went back to the "factory" low speed needle setting. I'm thinking if he had leaned the high speed needle a bit , the transition would have cleared back up and he would have been fine. BTW, I'm not ruling out an small air leak somewhere that affects idle much more than full throttle. Whatever the cause, it seems to me a real possibility that engine is telling krazyc that it's low speed is too lean.

Taking a huge risk trying to have two thoughts in the same hour, I'm thinking that the reason your landing approach idle rpm varies is because the prop load also varies. In the pits, we set a low idle and the prop is slightly loaded, pushing air. On your landing final approach, airspeed removes this slight load, thus the idle rpm rises a bit (the same thing happens on a larger scale when the plane is on a downline with the throttle at idle, but the prop rpm increases as it is actually being driven). As you said, "it just idles fast until the speed drops down". Get to stall speed, the slight prop load returns, idle rpm drops a bit. Mine does the same thing, and it's not unique to the brand, it's a prop load thing. The prop isn't actually pulling, it's just windmilling, and not contributing to drag, so the plane takes longer to slow down. Drop a couple clicks of throttle so it's not windmilling so much and the airflow is doing more to turn the prop, then the drag increases so the plane slows down better. When the prop load returns at touchdown, it might take a click of throttle lever to keep the engine running for the taxi back to the pits.