You may have seen a video of him cart around a 3 yr old on a lunge line but you perhaps did not see how much he was worked before that....
Agree with previous suggestions:
1) Hay only
2) Work work work
3) Lunge properly with gloves, side reins etc. Do whatever you have to as HE MUST NOT GET AWAY FROM YOU AGAIN.
4) Lead with a chain and use judiciosly if you must
5) Ride his little butt off. Your are most definitely not too big, he will be fine.
Agree with the other recommendations re feed, exercise & potentially pro assistance. He's a green horse and should be managed as such. I love the stubborn underdogs/greenies & think they can make spectacular horses, but its not easy.
Here's what I would do if I were going to tackle the problem. 1st- step back and teach pony that he should look to you for direction when you're on the ground whether that's lunging without a rider or when you're teaching a lesson.
Make obedience the stronger habit than bolting on the lunge line, which isn't easy because he probably thinks bolting is pretty entertaining at this point.
Put him in the bridle/chain set up you will eventually lunge him in again. I'd use an ultra long lead line but not a lunge line. Make him walk on the lead with his head at the appropriate position next to your shoulder. If he thinks about getting ahead, back him up. Banging the ground in front of his feet with a dressage whip can motivate the back up without touching the horse. Use your voice commands the whole time. Add some mental challenges to the exercise- ground rails, sudden turns, strange things to look at, etc. When you're ready, add some very controlled trotting to the exercises (i.e. a few strides toward a fence line so stopping will be easy). Think about how you train a dog to heal. Practice with him on both sides of you. Get your husband to do it too- so if you want his muscle later you're both on the same page. I'd do it a couple of short sessions during the day- again trying to build a broad habit of obedience.
After a few truly successful sessions, create a box with rails on the ground. Ask him to walk a straight line into the box and do a 180 degree turn around you while you stand in the center of the box.. Ask him to halt as many times as you want as he does the turn. Whatever it takes for it to be successful. As soon as he's completed the turn, walk out of the box. Make it a part of the flow of the exercise. Again practice on both sides.
Once you've got to the point where these exercises are almost boring, then ride him until he's tired and follow up with your ground exercises. This is when its important to have done all the ground work in the set up you'll lunge in. Begin your 180 degree turn exercise but ask him to keep walking around the circle. Do it once or twice then move on to another part of your ground exercises. Don't let pony think you're doing something different, it's just another part of the ground work. Come back and add one more circle. Change sides. Do lots of walk/halt transitions on the circle. Move back to your ground exercises and have a helper roll your rails out a bit to make the circle a little bigger. Go back and do the same walk/halt circle giving him a little more length on the lead line. Repeat the cycle building to trot/canter but only as you're certain you'll be successful. Don't push your luck. Stop when you can tell him what a good boy he is for listening.
I have a crash test dummy if you want to borrow her. She likes naughty small ponies and has no fear. MD isn't too far for us to pop up a time or two. She's long but lightweight enough for a small pony (115 soaking wet) and still bounces when she hits the dirt. Although nothing has scraped her off in a long time. She really actually enjoys evil small ponies.
GaMare has great advice for dominating His Ponyness on the longe line. Here's another equipment suggestion, and it's the only piece of Clinton Anderson equipment I'm likely to ever own. I am NOT a natural horseman wanna-be, but the placement of the knots on the nose really help when you've got one who wants to get loose on the longe line. And when your longe line is attached to the halter and not the bit, you can dig in your heels and pull against them until they stop. Together with a small circle to start and a longe whip, you can control all his avenues of escape.
I bought this halter for a horse who kept getting away from my on the longe line. My ring isn't fenced, so getting loose was beyond unacceptable. A couple sessions with this sucker and he wouldn't think of leaning or tugging on me.
I generally put it on over the bridle if I plan to ride after longeing. The real trick is to get it tight. You don't want it sliding all over the place. The throatlatch should come right up the groove between the jowl and the neck, and the noseband should be relatively high on the face.
Life would be infinitely better if pinatas suddenly appeared throughout the day.