First of all, you don't have "gears". You have a CVT, which means Continuously Variable Transmission. What you are likely describing is the torque converter locking up. That happens between 15 and 20 mph.Alright, just following up. Still can't find the problem. Can you give me an idea of where to go from here?
The thing is on that on the thread Glenn linked me, that guy is having a completely different problem than I' having. I understand they may be linked. My car isn't doing any of the things his was.
Summary from his thread:
"Driving out of a parking lot when I believe I rev'd higher than usual in 1st and in 2nd gears. Shortly after, lightning bolt flashed numerous times. The car felt as if it was in limp mode...minimal throttle response, difficult to reach normal driving speeds. The vehicle idle was very rough, throttle response back to how it was prior - non-existent."
Back to your problem. Now that you have the other stuff out of the way; the next thing is to clean the throttle body. If it's sticking it will not track the computer's direction properly and the computer will try to compensate and the results will be jerking and lack of throttle response. If cleaning doesn't work; it likely means like the other person found out. The throttle body was bad and needed replacing.