for a while now when I start my fc40 the quad will sit and idle as long as I want. But once I have taken off and come back and land the motors will idle down but only for a few seconds then they start to speed up. I am forced to hold my throtle in the down postion until it stops all together. can anyon tell me why this could be happening? I looked at my setup in Naza and the motors are set in common speed for idle and also set for itelligent. Any help would be appreciated.