I have a 13 year old Standardbred gelding who was a harness racer when he was younger. Then, he was not touched for 7 years until I got him last year. I have been riding him for the past year, but I just started driving him again about a month ago. He does really well when he's in motion... I trot/pace him 4 miles every time I take him out, through a lot of traffic and distractions without blinders on. He does really well. He sidepasses and all that, but the one really annoying/dangerous thing about him is that he absolutely will not stand when the cart is behind him. If you stop him and try to stand still for a few minutes, he jolts forward or backs up, and when you try to correct him by pulling the reins or slapping them on his hindquarters gently (I don't carry a whip with him), and overcompensates and does the opposite. He just goes forward a few steps, then back when you pull, then forward, then back, etc....and if you pull hard or fight with him for too long, he will rear. He does that a lot, and it scares me, because I have seen him fall backwards before and he did it in heavy traffic earlier today. Please help!