I suspect you are right about the respect issues and I have worked hard to overcome that with his biting, and striking, but obviously not enough. I will try driving him as you suggest and see how that goes.
I have had him and his teeth vet checked since he has been home and so I am confident there are no physical issues. When he came home, the corners of his mouth were quite raw though and I waited for them to heal before doing anything else with him. Could something like that also have an effect on his current behavior? The trainer used some type of twisted wire snaffle the one time I saw him ride him. He called the raw spots raspberries and said they are common?
I have thought about selling him, but would like to see this through as I have already invested a lot of time and money and I do love this horse in spite of himself.
Thanks for taking the time to respond, your advices are appreciated.

~Lorna