Some things cannot be fixed. I urge you to get a qualified behaviorist (veterinary) to evaluate him. If he is truly unstable, rehoming him is not fair to him or the new home.
TX-Houston-Possible Female B Mix in Shelter
This young red & white girl is listed as a pit bull terrier mix but looks like a B mix to me. She is spayed but looks like she may have had pups recently. She is at BARC Animal Shelter & Adoptions which is the City of Houston shelter. The shelter took in over 200 animals in 10 hours since Tuesday. Could someone call to see if she is still available and check her out? I doubt she will be there much longer because of her listed breed and overcrowding.
Here is her PetHarbor page: