Chris, I've been reviewing the posts below. If you don't want to replace it then reinstall your jamb and start with it being level on the hinge side.
What I do in that situation, is find all previous buried finish nails and drive them on through with a nail set. Remove the casings. The jamb will be loose in the doorway. Get new shims and reshim and reset the door jamb. Nail through old holes if you can but if not fill in all holes with putty when done. Reinstall casings. If you need to rehang the door to match the rehung door jamb then so be it.
Hopefully the opening hasn't shifted so bad that the casings still cover over to the wall. Good luck.