Hello, I have a problem with 2 motors on my fpv drone I recently built. Everything works fine until I arm the drone and give it some throttle. Arming works perfectly good the motors are all spinning at the same rpm's. When I apply some throttle (about 10%) I just lose control and there is the problem. 2 of the 4 motors start to increase very fast the RPMs while others stay at the same I sent with the radio. When I try to set the throttle to zero the motors just decrease to 50% and the only way to stop the drone is to disarm it . A while ago it happened the same with motors 1 and 3. I checked every wire, controlled the accelerometer, and calibrated all the instruments. I even reset the radio and receiver. What should I do?