I have a suggestion- although I am not a trainer, I have a young horse with energy to control and have been fairly successful so far. It sounds to me that your horse is paying more attention to his surroundings than to his driver. A trick I learned is that you always have to keep an hear cocked back to you to know that they are engaged in the conversation between you and the rider. When your horse gets quick, I’m sure his ears are forward aiming towards his target horse he wants to race. Instead, bend him towards the inside with constant inside taps of the inside leg and squeeze the inside rein until you see his inside ear c*** back. When it does, it means that he is listening to you. Praise him with a calm soothing voice and stop the aids- this allows him to understand that when he pays attention, he is good. As soon as his ears go back forward, you need to regain the attention with the same technique. Do this over and over and make sure to PRAISE and stop asking when he gives you his ear. Consistency will re train him to be listening to you and not his surroundings. With this method, you are constantly riding and aware of your horse. It can really improve the relationship of leadership between the two of you though ( in a kind way).