ORIGINAL: pe reivers
After each idle re-tune, you must set the H-needle again. It seems you are too lean on the top end, and your mixture is mostly provided by the idle needle.
Set the engine at ~1800 with the idle stop screw. Then find best idle rpm with the idle mixture needle. Open up 1/8th turn from there.
Now turn your attention to the high needle. close until rpm sags, open up again until rpm is just a tad off max rpm. If the carb is OK, transition should be OK. If not, dismantle the carb and clean the transition spray holes well. Blow some fuel in the carb and check function of each jet. There should be three or four of them, apart from the main jet.
First I don't use the idle stop screw, I have a digital servo on the throttle, if it touches the screw it pushes with full power against it and will burn out, ask how I know that!:^(
I thought no way is the idle set too rich, but if I ask for help I listen and try what is suggested. It turns out somehow with all my putzing around the idle screw was set 1 3/4 out, the H needle was set about 1 turn out[:'(]. So to start I set the L at 1 turn, the H at 2 turns. I started it, then adjusted the H to get 7000 rpm, then set the idle on the radio at 1800 like Pe suggested and popped the throttle open, a little on the rich side, I played with it until it was about 7/8 on the L. Now it's working pretty well, 99.9%. So tomorrow I'll fly and fine tune it.
Thanks Pe.