Flymeaway, if you are having troubles in the air but not on the ground with run-ability then it is an air pressure problem on the carb, also as mentioned some of the carbs that came with them had very loose needles leading to problems also. If it is running hot also look at your baffling and and especially air flow, a lot of people do not pay much attention to that and any high performance engine needs a little extra in the cooling department.
I have one of the first ones made and it has not missed a beat, very smooth/linear running and gobs of power