Check two things. First, check you're ATV's, I think they are called EPA in surface radios. Look to see if both sides are about the same. Full throttle to brake needs to be linier, Or close to it. Adjust the linkage so it is. It's an old heli thing!!! Next, check you're expo. It sounds like you have negative expo in it. Center it up. Before we had computer radios with helicopters, we had to set them up mechanically. Then came the computer radios of today. In nitro helis the throttle linkage is very, very critical to proper throttle curves. Nitro engines are no different in cars. Yes you can adjust with the radio, but you will feel the difference in the flying or driving of you're toy if you mechanically set it up first.
MBX7r, 22, M-11