Lots of great advice, thank you to all who have contributed. He is outside today, running and loving being in pasture, with a raised voltage fence that has a new, higher strand that he can't jump. I'm calling the vet this afternoon to set up gelding.
As for feed, he gets 6 flakes of hay for a 24 hour period. Plus at night he gets two cups total of- hay stretcher 70%, oats 25%, and corn 5%. I don't feed any sweet feed or molasasas products.
I have made a point to not back up from him, and have actually been getting him to stop and think about it when I make him back up, so I have a renewed confidence that this will work, after alot of hard work on my part, and good advice. My vet happens to be a trainer as well, so he's going to help me work.
Thanks again everyone!