I have an 04 Grand Cherokee that has a powersteering whine and poor assist at low speeds, and it has less assist the closer to the stop that you get. The pressure hose shakes badly. I do not have pressure gauge but I think that it has excessive pressure when turning the wheel. I am stumped because the power steering runs the fan also, I suspect the steering gear but has anyone seen this before?

Have you tried changing the power steering fluid and flushing the system? It's not uncommon for power steering pumps to go bad, especially if the fluid is not changed regularly (60,000 miles). They generate much more heat than many realize, which is why they have their own cooler. Once you solve the problem, I would use Amsoil Synthetic Universal Power Steering Fluid:

http://www.amsoil.com/storefront/psf.aspx

It will help the pump and rack & pinion to run cooler, quieter, and last longer.

Chrysler Power Steering Moan

Go to "internetautoguide.com" I noticed a recall for the 2004 Jeep Grand Cherokee of the steering gear box. If this is the case and you're the original owner, it should be a freebee.