why my horse will not stop when galloping/ running

Question
Well our family owns a racing horse that was sold to us a wile ago.And our parents have lived on a Mexican ranch since they were born and have a very good experience with horses and other farm animals. We live next to mountains/deserts and normally go riding there with one or two of our horses. We had not recently taken the horse that we are having problems with to ride for a wile, and when we did we had some trouble making it come to a stop. Some friends of ours that are charros(like Mexican cowboys ) say that we should try using the kind of bridle that the horse use to use with its old owner,(we use western saddles and other equipment for the horse instead of the English kind) and that it would probably help a little or make a difference. we tryed that and it didn't make much of a difference. what do you think we should try or what advice can you give us to improve this problem? Or advice?

Answer
HI -- I WOULD USE A RING SNAFFLE BIT. IT IS NOT TOO SEVERE AND IT DOES GIVE YOU SOME CONTROL ON THE HORSE. YOU CAN ALSO TRY A MARTINGALE WHICH WILL HELP HOLD THE HORSES HEAD DOWN WHEN RIDING. I ALSO WOULD HAVE THE HORSES MOUTH CHECKED OUT AS HE MIGHT HAVE SOME PROBLEMS IN HIS MOUTH. HOPE THIS HELPS  THANKS ED HESS