Popriv.. How new is this engine? If it's brand new.. meaning, only one or two tanks run through it, it might just need to be run and flown.

Take it up, being careful not to go where you can't land it should it dead-stick on you, and give it some flight time. I wouldn't be surprised if it improved with each complete tank burned through it to the point where it has good idle, good transition, good full thorttle power, and good idle back from full.

CGr.