The problem with all of this is that model airplanes have not studied aerodynamics. They just don't read all of your theories.
But Ron Moulton, a famous modeller, once wrote "downthrust is the modeller's friend".
This is really basic stuff:
If your airplane climbs when you add power, put in downthrust until it stops doing that. If the amount of downthrust you have to add ends up being really silly, change the stab(or wing) incidence. But chances are you won't have to do that.
Downthrust is what you need.