My 2-stroke experience is not translating as well as I thought it would with my first 4-stroke.

Fuel: PM 20/20 (always fresh)
Plug: O.S. F
Prop: 12X7 APC

I have the high end at 1.5 turn out. This seems to be a common setting for this engine (right?) and it averages about 10900 - 11200 rpms there, with a nice smoke trail, and excellent power. The low end is giving me some problems.

I get the engine to idle at around 2200rpm. I roll the throttle to full and back to idle, and it will hold it there. But after 20 seconds, I roll to full and get hesitation. It goes to half throttle rpms instantly, and then slowly CREEPS to full thrrttle rpms. Then when I go back to idle, it's at 3000rpms. Frustrating. This hasn't effected flight much, because I'm never at idle for more than 5-7 seconds or so, and the engine runs superb, but I've heard it should hold a perfect, consisten idle, and maybe I'm going about these settings wrong? The needle is set around 2 to 2.25 turns out, and this seems like a lean setting, but when I turn it in to 1.5-1.75 turns out, the idle creeps up, and YSDoctor says that's a sign of richness. Any suggestions?