Welcome to the Forum!! :)
What kind of shape are his feet in? Is he due for a trim? Has he been trimmed correctly? Are there any conformational irregularities with his feet (club foot, etc.) or old injuries? He's a TB - was he ever raced, I.e. Any old racing/training stresses/injuries?
What exactly are you asking him to do when he trips? Just ambling along, actively walking, trotting, cantering... ?
If his feet are ok, then my guess is that he is simply offbalanced, something that good training will help as he learns where to put his feet and how to move. In the meantime, recognize when you might be asking for something that could compromise his balance too much too soon. For example, if he's having trouble at the trot, don't expect it to get better with speed.
A stubborn horse walks behind you, an impatient one in front of you, but a noble companion walks beside you ~ Unknown