jittery flight p3p

Hi all! I am rather new here but have been droning for a while. I am really frustrated with my DJI Phantom Pro 3. Not only has the video been jittery, no fix seems to work. I tried with the gimbal, resetting, updating the firmware on everything, doing IMU (twice), and everything in between...

Hi anyone know why my p3p flys iratic? It's goes up ok but when hovering it zips to the left and back like it's correcting itself all the time. I have done an imu calabra tion an show everything ok . Latest updates and compass cal. I bought second hand in brand new condition so I'm gutted ...