You describe two different things. I am guessing that I am not understanding for one of them. A video of oscillation and flight spin would help.
Spin in flight is usually caused by all motors spinning in the opposite direction of the way they should spin. When switching from some other brand of firmware to LP, you must make sure that motors spin in correct direction and that correct props are put on the motors. Two wrongs do NOT make a right. You can't spin all the motors the wrong way and compensate by putting the wrong prop on each one.
Two diagonally opposite motors must spin one way and the other two must spin the other way.
Look on Vehicle page for picture of motor rotations. If motors are all backwards and props are all backwards, there is a check box there to allow you to just use it as it is.