is it a stutter up-to quarter throttle, or at quarter throttle. if the pilot is too big, you'll notice it right from idle, and your airscrews won't adjust up right. if it's @ 1/4 throttle, then it's in the needle. from the top hesitation, i would double check the mains, and play with the neeedles some more, and remember, the needle will seem to work good in 3 different spots, and you get it set for 1/8 throttle on up, then set the pilot.