Very little resistance in the steering wheel

I've got an '01 XJ with about 158K miles on it that has what I would describe as "super power steering." It's almost as if the steering works TOO well, which invokes a sense of fear when I'm driving at highway speeds as I grasp the steering wheel tightly to make sure it doesn't take off in either direction - not to say that it will, though. In fact, the truck doesn't pull to the left or right, doesn't have any bump steer, and is otherwise normal. The problem is, if I just tap the steering wheel in either direction, it'll spin until the wheels hit their lock.

So, it by no means feels like I have sloppy steering, which I would attribute to worn ball joints, tie rod ends, or even wheel bearings. I'm thinking more along the lines that the steering gear box is very worn and needs to either be adjusted or replaced. I noticed that there is an adjustment screw of sorts on top of the steering box, but I've read it's often a bad idea to mess with that. Basically, I was wondering if anyone has had the above described symptoms and had fixed it by doing something other than purchasing a brand new gear box (I don't want to do that quite yet, but will if I have to). The truck needs to pass inspection this month and I don't think the resistance-free steering wheel is going to fly with my local inspection station.

i have worked on a few vehicles with that same problem. they were all the valves inside the steering box/rack(depending on the type of steering). basically what is happening is when you turn the steering wheel, it opens a valve inside the box allowing the fluid to flow in that direction and assist you with turning the wheels. when you stop applying pressure to the wheel the valve closes so the fluid does not continue to push the steering. what is happening in your case is the valves are sticking and doesn't stop pushing on the tie rods. there is no adjustment for the flow so you will need to replace the box.