Hmmm...he doesn't pay attention to you and chews on the bit. If his teeth are ok and the bit is in the proper place, I would say he needs lunged to get the excitement out of him. Let him play on the lunge line.
Another thing my trainer does with some young horses is put a rubber bit in his mouth and let him chew on it for awhile. Then when you ride him, his mouth will be tired of chewing.