I had a young gelding that would spook at anything and his first response was to bolt. Once he got going he would not stop. I decided to just let him run out of it one day in the field and 3 laps of the quarter section later I finally had to stop him because I think he would have gone all day.
I dealt with him by circling him every time he spooked or even thought about spooking. You have to interrupt their thought before the take off, get them circling and thinking about something else. Every time he spooks just pull his head around and circle him until he stops, as soon as he stops release the reins. If he starts moving again circle again until he stops. Once he is calm and will stand on a loose rein go back to what you were doing when he spooked.