So Right now I have tow 2nd gens. Both 4x4 5 speeds. 
 

my 99 has always had an issue with power steering at idle mostly. I replaced the pump with a Borgeson, all new power steering lines with a filter, red head gear box, synthetic fluid and rebuilt the vacuum pump while everything was out. I still have barely any power steering at idle. I even modified the Saginaw pump by drilling a larger hole. 
 

my other truck with an all original power steering pump, lines etc has had 37s (back to stock now) and it could turn those tires without an issue even at idle. 

 

I am beginning to think the truck with the issues has a hydro boost blockage of some sort. My brakes work fine and I have no codes or anything of that nature. Could a blockage in the hydro cause this issue? EVERYTHING power steering wise is new along with most of the front end. It’s almost impossible to hook to my trailer since I can’t turn at a stop. I gone crazy trying to figure this out and I’m thinking of replacing the hydro to see if it solves anything. I have flushed the power steering lines several times as well
 

Anyone have any ideas? I have had abs driven many other 2nd gens and have had no issue with any size tire. The truck in question has 33s so nothing crazy.... 

 

 

Are you using a standard ratio box? Do not use a "quick ratio" put way too much strain on the gear box. Then with larger tires it makes it weaker. Standard ratio is lower geaed and easier to turn with larger tires. 

 

All I'm running is a Blue Top Quick Ratio, NAPA power Steering fluid with a NAPA power Steering pump. No filter. My OEM pump lasted 425k miles. Only running 245's (30.5 inch tires). Only change fluid every 30k miles.

 

Something in the steering box power valve assembly? If there is debris blocking the port to deliver fluid to one side or the other it will be restricted making it worse.

 

I woulds consider swap out of the synthetic fluid, go back to petroleum base. Might be a bit better for pressure. Never had a pressure problem with standard power steering fluid where I've seen several with synthetic possible reason maybe. Make sure you not using ATF! No designed for it. 

 

Since power comes from the hydro booster is there any thing plugging a port in the hydrobooster restricting fluid flow? Plugged port, hydrobooster spool stuck partial?

 

Power Steering Pump -> Hydro Booster -> Power Steering box 

Since the box is a recon, that would be suspect. I don't think the hydro can block anything. I assume the pump is new, not recon.