Morning Bax!

I've been having some troubles with my 2 year old engine regarding transitioning from idle to midrange. Background follows"

Received NIB 2002
Broken in according to manual
Started using Cool Power 15% fuel, switched to 10% Fuel for 1 season since it was given as a gift. Has had 3 gallons of fuel run through it.
Remote needle backplate has been replaced 3 times due to crashes
Turning 11X6 power point and Master Airscrew propeller since installation in Avistar (in 2002)
OS #8 plugs only

The engine ran great in the beginning, but in the last two summers, when I have started it and tried to go from idle to 3/4 throttle for takeoff, it dies at just under 1/2 throttle. My Instructor is puzzled why this is happening. We have both changed all fuel lines, verified there are no air leaks comming into the carb (no bubbles in the lines) and have changed the glow plug numerous times trying to fix this problem. It will even do this while the ignitor is still attached.

He has also made adjustments to the carb needle, but to no avail. We were flying at an exhibition yesterday and out of 8 flights, 3 were deadstick after getting up to altitude. This was after numerous missed takeoffs due to not being able to get past 1/2 throttle.

I took it out of the A/C last evening and took it apart to verify there weren't any issues concerning the piston/lining and bearings, all looked good with no scoring or pitting. I removed the carb and verified that the "O" ring was still serviceable and put a bead of red RTV sealant around the carb to crankcase joint.

Can you offer any further insight or advice with what may be causing this engine to run this way?

Thanks alot in advance!

Don