Hello out there,

I am new to model airplanes, specifically with 5 half flights (half because take off and landing was accomplished by an experienced person) and 2 complete flights (landing was a bit clumsy yet with no casulties
I have the following gear: Phoenix Domino trainer, TT Pro 46 and Futaba 4EX transmitter.
Everything works perfectly except from the fact that TT Pro hesitates a little when going from idle to full throttle. Specifically, when going from full throttle to idle and immediately to full throttle again, there is no problem. If the engine idles for about 10-15 seconds then the transition is not smooth (sometimes more, sometimes less).
The engine never died during flight or on the ground. The idle is very good and steady and the full throttle perfect. As a beginner, I use the engine half throttle during flight.
Regarding the fuel system, I have not seen any bubbling and the fuel tank is ok. I have refurbished the tank by replacing the plastic pipes (one of them was broken) with copper and tested the tank for leaks by immersing it in the water.
A friend of mine told me that the carburators of these engines have only idle and full throttle trimming (low and high needle) and that middle range throttle behaviour of the engine depends on these settings. He also suggested that 10% nitro fuel will compensate on this after finishing the fist gallon of 5% nitro (so as engine to break in smoothly first). The fuel is Cool Power.
Is this transition problem caused by the fact that the engine is not completely broken in (1/3 galon ran through it) or the 5% nitro ? Or both ?
Also, do you think that it is good to break in the engine by flying it at half throttle on the air during training season (the high needle is set to slight rich) ? In fact, the engine was broken in also by running the first tank on the ground.
What is your opinion ?