My horse had a similar issue, gotta love TBs. He would "race at the trot", pull, take the bit, you name it. with him we did a lot of transition work but also using as little rein as possible so he doesn't really have the chance to lean. There was just enough contact for half halts but not enough to make him uncomfortable or enough to really lean into. Also try lunging and doing so ground work with verbal commands. Don't lunge him so he's extremely tired just enough to get his excess energy out and get him listening to you. The ground work with verbal commands will transfer under saddle so if you tell him whoa he will eventually figure out that means stop no matter what. As well as saying walk, canter, easy, etc.