As another poster suggested, sounds like she maybe tip stalling. Its possible to stall a wingtip even at higher airspeed if the angle of attack gets too large. Wondering if your wing is warped somewhat (those wonky spars look kinda scary). If the wing is strait then maybe she's favoring a right roll when she stalls due to prop torque *shrug*. Lastly you may want to mess with the CG. See if that helps any.