I am having troubles getting my YS 170 to transition after the first flight/run of the day. On the first flight of the day the engine transitions great with no problems. The run up on the ground sounds great and it takes the throttle great on take off. But after the first flight of the day I begin to have problems, the engine won't transition. It starts to go lean and tries to spit the prop in the mid range. The enigine will idle for 1 min 30 sec. before it starts to load up a bit. Now I can get the engine to transition to full throttle by working the throttle stick and the engine is not lean nor rich on the high end. Only the mid range do I have problems. Now I have this problem after the first flight of the day on the run up on the ground and also on take off, it goes lean in the mid range but does advance to full throttle. Once in the air the problem goes away. No more transition problems in the mid range. Fuel: Cool Power 20%. Any help would be great.

Matt