Quadcopter yaw issue

I have built a quadcopter, and as a control unit I chose Pixhawk Cube black.
I configured the vehicle through qgroundcontrol, and flashed the latest px4 firmware to controller.
Quadcopter can hold stable yaw angle, but the problem is that motors 1 and 2 (see airframe reference) have much higher rpm, than motors 3 and 4. Motors 1 and 2 have about 1700 PWM values, motors 3 and 4 have about 1300 PWM values, thus motors 1 and 2 are much hotter on the end of flight.
When i move yaw stick to the left, drone is reacting well, butt sluggish when the yaw stick is moved to the right. I have tried flying with different controllers, and different quadcopter configurations, but result was the same. I’m using T-motor MN2214 KV 920 BLDC (Graupner C-prop 9x4 inch).
What might be the problem? Thanks in advance!