Classroom Fighters - Porpoising

It sounds like you are describing some porpoising behavior. You can reduce the porpoising by flying slower at low throttle - which you pretty much described if I understand what you said above. You can also try initiating a turn as the plane is starting to climb to the apex of the porpoise. This will usually eliminate the porpoising and you should be able to get the feel of the throttle eventually and eliminate all porpoising behavior without having to initiate a turn with the rudder. Soon you'll be flying exactly where you want the plane to go and will do it without thinking

Since these are controlled by throttle and rudder only, it is nice to be able to climb out of trouble, but if you find you are porpoising too much, you can always bend in a little down elevator - try about 1mm of down elevator and test fly. You do that by simply bending the foam a little bit at the tail. If you do this, you'll notice you now have more of an "interceptor" type flying experience. I like it, the fighter then behaves more like a real aerial predator. Thing is, if you do this, you might lose some of your ability to climb if you need to. So you'll be flying a different pattern than you would be if you did the opposite elevator adjustment, for example.

By adjusting your setup before a dogfight session with your friends, you can get the upper hand in the battle, so it pays to learn all about trimming and adjusting your airframe for performance. This is particularly true with the Rudder-Throttle controlled Classroom Fighters. Don't be afraid to bend the foam a little bit and see what happens. The plane can teach any R/C pilot a few new tricks in this way.