Really sounds like your plane is nose heavy. Nose heavy planes have a tendency to pitch up as the speed increases. This also means that the stabilizer is not at the right angle for that CG placement. I wouldn't mess with either the stabilizer angle or the thrust angle. I would move the CG back a cm at a time until I got the flying qualities I wanted.

WARNING: When you do this the aircraft will become more and more touchy, especially in pitch, if this is not what you want then you need to reduce your elevator throws to compensate. Eventually you may run into a situation at which your aircraft actually pitches nose down when speed is increased. Bottom line, move the CG back a little at a time until you reach the desired qualities, but be ready for these changes.

An example, I have a Four star 40 that I purchased, i flew it for a while, made a repair and flew it again. I didn't check the CG. My plane was and still is tail heavy, it is almost neutrally stable and is very, very touchy. When I over speed it it wants to pitch down. These qualities might sound undesirable, but I have come to expect them and understand how to correct for them, and now I have a Four Star that can do some absolutely astounding maneuvers.

It's all a matter of preference.

Nmking09