Hey freak I still think you have to much pitch and not enough thrust to pull it in the air. the Four's need the higher pitch because of the lower rpm. I would try an 11.5x7 bolly or an apc 12x7 and cut about 3/16 of the tip.
The nine pitch is to much for the drag of this plane if those props are not enough in the air the increase the dia. by one inch. the extra trhust will help in the corners and then unload more in level to get your top end. have some one with a radar gun to verify speed. This is what I would do and it is your plane, these are just suggestions.