How much daily exercise (free running) is getting each day? I find with the pures anyway if you don't give them enough they will take it for themselves.
If you are the boss there will be a distance from you to your dog where he will not attempt to disobey you, I think you need to start keeping him close very close and call him back to you and release him to that short distance, when he responds give huge praise, high pitched sqeaky voice the works, if he doesn't instant fury roar at him, the minute he stops and reponds squeaky and praise again. You are aiming to give the clearest must unm