He sounds immature, like his training has been rushed at some point, so he just doesn't know how to behave under pressure.
I would take things right back to basics, stop jumping him for six months and work on the flat and ground manners. I would take him to tiny local shows where you can do...
I have mine! And he will be with me for life (he can't be sold due to various issues) so if I can no longer afford him I'm afraid he will have to be pts... Very expensive lawn mower that he is... Love him to bits though :)
Another vote for ex racers!!
I just bought one for £2500, probably could have got him cheaper, but he is a star :) 8 years old, sane scopey jumper and starting to work in an outline. He's also very striking looking, no-one believes me that he's a thoroughbred, as he has such good feet, is so...