When I get to altitude and bring it back to flight idle, I feed in full up elevator and my airplanes like to porpus. My 1/4 scale and my profile airplanes, the planes will pitch up and stall, drop the nose and pitch up again, stall drop the nose over and over. Is this an indication of not enough aft CG or not enough elevator throw or both? I don't get it. I do have 45* throw on my full rate elevators and the CG is already pretty far aft. Do I need more of each?