Does it have a remote resivor for the power steering fuild? If so I have seen the fine screen on the bottom plug up and starve the pump for fluid. ( sound like it is out of fluid but isn't) Has the fluid ever been replaced? If you have a mechanic's stephascope check the pump ( place the end on the pump and have someone turn the steering wheel) if it is the pump you will know.
Rogue Cell #8