Boy, that does not sound like fun! It sounds like your pony has some serious trust issues. I don't think he's happy and excited -- instead, he's anxious about jumping and rushing to get over and away.
Assuming that you've checked all the obvious physical problems that might exist -- poorly fitting saddle, bridle, bit, or girth; teeth or feet that need attention --I'd recommend that you start over with the basics, walking and trotting over single ground poles. Maintain a steady rhythm, and intersperse randomly scattered poles with your flatwork, so you perform lots of transitions (walk/trot, trot/walk, variations in speed/rhythm) with turns and circles. Keep a light contact, use a small crest release as he steps over each pole, and reward him with good words and pats when he relaxes and keeps the rhythm. If he rushes or anticipates, quietly turn away from the next pole (but don't do it abruptly; just focus your eyes on a turn and ignore the pole as you direct him around it). Do plenty of downward transitions (trot to walk) both in front of and after a pole; again, don't wrestle with him, just ask quietly and if he still wants to rush, turn him quietly aside. When he does give you a relaxed response, reward reward reward.
This has to become almost boring. When he's listening and relaxing, shange the appearance of the poles WITHOUT raising the height or cantering. Add flowers, place a towel over the end of a ground pole, trot over a pole that's positioned between barrels, etc. Same stuff -- slow, steady, lots of transitions.
Progress to cantering over the ground poles before you raise the rails...get the same quiet response, then move to actual jumps. Again, trot them first, then canter.
Grids and gymnastics can also help your pony find balance and trust you, because in a grid you must loosen the reins and let him find his own balance without micromanaging. For more ideas, read my book, Jump with Joy. It deals with troubleshooting many such problems.