Curves are not adjustable for that radio... it is what it is for that.

Is your throttle trim all the way down? it can act 'lazy' or 'late' on the throttle. move the trim up.

Is your pinion gear (on the motor) tight??

If all else fails, I'm willing to bet you have a bum battery... You may think it's fully charged, but a junked battery can act this way too. Don't over discharge the battery and charge it 1 hour AFTER you've been flying... In other words, let the battery cool down first before a recharge.