What gyro are you running? Is it a head/tail lock gyro? You may already know this but if you have a locking gyro your do not need any revo mix.

Definitely sounds like your low end needle is to rich. Its located right inside hole in the center of the throttle arm. Turn it in about 1/4 turn and try again. If it improves but seems to still need some adjustment turn in more but in smaller increments.