ORIGINAL: ABELL
[
] We can make the engine run fine at full throttle and at half throttle, but when we bring it back to idle to land the engine dies!
That doesn't indicate a lean in-flight condition -- note it only dies when throttled back to idle.
Aside from low-speed mixture tuning, the idle speed may be set too low. Try cranking up the idle speed a bit (slightly greater throttle opening at idle).