H9 has pretty nice planes. I have had and still have several. That being said, any manufacturer can have a lemon come off the line. Check for any obvious construction errors with the fire wall. Your discription of the flight characteristics is indicitive of a thrust line issue or a very nose heavy plane. You may also have an assembly issue. If you added resin to fuel proof the fire wall and have a blob of it behind the mount causing the engine alignment to be off. Engime mount screw loose? Check all these and anything you can think of that would throw off the engines allignment.