This may not be related, but how are you priming the system? I have the 4.7 and my first replacement pump didn't seem to work...
It was only after I read about priming the pump first, with the motor off, that I finally got my power steering back. With the car off, did you jack the front wheels off the ground and turn the wheel back and forth a bunch of times, while maintaining the fluid level in the reservoir? Then, put it back on the ground, start, and cycle several more times. I ask because my first attempt at installing one of these resulted in no power steering... until I completed this procedure. Again, may have nothing to do with it, but since I just went through this, thought I would share.
Oh, and is the hydraulic fan spinning? A lot faster with AC on?
2003 4.7 4x4 WJ Limited. All stock.
Future Plans: 242HD Swap, Budget Boost