Haha my Flash does the same thing to the pasture but the lady before trained him to slow and he gets worked up outside the arena, as she never road him outside. Adn I walked him down the road with just a halter and lead and it seemed to help I will jump on and make him walk every once and a while he eats. And he seemed much better, I do loung work with him twice a day when its not REALLY hot out like its been and I ride once a day. And really get after him when he tries to get away with things. Make things hard where he wants to be and easy where you want him.
I did this in the pasture when he wanted to go to the others in the pasture next door. I trottted and did circles near them and walked and did troting in larger circles away from them and he would walk away from them in the end if I asked and after some walking I got off and put him with them.
The horse I'm riding is "gate sour" and what we do is everytime he makes a turn on his own (meaning he isn't going where I told him to AND is probably headed for the gate) I turn him the opposite way. At one point we were doing figure eights with my teen son. He would get him on the fence, then Chopper would turn in with his head and we'd tell him to turn Chopper the opposite direction and back to the fence line. Took awhile but he quit trying to go to the gate. Maybe something similar? As soon as Flash starts to head for the stall, turn away and walk the other direction. Then start the way you wanted to go again and repeat?