I agree with Hover259 - make sure you check the balance; sounds alittle tail heavy (mine exhibited the same behavior until I rebalanced it).

Also, I wanted more authority while flying so I increased the 7 cell 720 mah (Nmh) to 8 cells. At first the motors ran great - then, 45 seconds later - I fried one of the motors. Yikes!!!! I have spoken to several others who have tried the same by going to an 8 cell (9.6 volt) and had the same problem. I went back to the 7 cell and it works fine. Also, I built it witout the landing gear in order to save weight and for a more realistic flight. Good luck flying it - it really turns the heads at the field with the low flybys and sweeping turns. It is a very fun plane to just cruise around with!