I have the Seagull 540 with the 66.9 in wing span. I had been flying it about 2 months ago and it was fine. Went to the field today and had major problems. I have the O.S 120 FS 4 stroke engine and my RPM get up to 9700. I have a Master Airscrew K-Series 14x6 propeller. My CG is 6.5mm from the leading edge it balance good. Now the problem I'm have is when I take of it flies like its under power real slow and sort of tail heavy. Can only make one lap and have to land it. Please!!! any help will be greatly appreciated.

Thanks,