Welcome to the Extra Easy climbing school. This is a know "feature" with this plane, even one of the popular reviews identifed this in it report ( can't recall which one now, but if you really want it I can find it). I used about 3-4 popsicle sticks, and proper balance with nose weight, and its better. I might try a few more to make the bottom of the wing parallel with the rear stab for better results ( ie more sticks).

I played with many levels the downthrust but it did not correct the situation. As a previous post said, I agree that it is designed to climb at full throttle. I'm still curious to hear if anyone has completely eliminated this feature so that it flys consistent at any throttle level.