My horse does this as well, my instructor told me that my warming up and my flat work is really important before jumping, it prepares you and without flat work (the boring stuff) your jumping won't be as successful.
When you're warming up, have a firmer contact, get him forward, then half halt and slow him down, then speed up and slow down repeat this again and again in trot on both reins then do the same in canter. What you are doing is getting him listening to your aids, so when you are jumping and he gets too fast and you slow him down he'll be able to relate it to the flat work.
If he doesn't listen to you when your jumping and he's running on you just halt. Also if he's getting really worked up and excited when jumping, set up a small jump and take him over it in trot, halt after the jump and if he was able to halt like how you expect him to, give him a pat. Turn around where you are and go back over the jump, then halt. If good - pat, if not turn around and do it again. When he's behaving like how you want him, canter and repeat.
Hope this helps - good luck!