Double check engine idle RPM and make sure it is not over 2000. A higher than normal idle causes all kinds of trouble during landing.

I land my 50cc Extra or Edge by initiaiting the process about 100 yard from the pilot's position and throtle down. Then fly the 180 degree circle to land it (aka IMAC style). During 80% of the 180 circle, the throttle is set at a little bit above the idle to kill speed. It is for the remaining 20% I need to throttle up at about 20% on and off to provide enough lift.

I have used Menz, RCShowcase and Vess Props. Seems to me throttle management and the fly path are the key to a perfect landing.