I have an early production 91 (man. 5-90) 4X2 Explorer 4 door that seems to be overly agressive in the steering department at highway speeds. It has done this since new. Any small movement in the steering wheel is transmitted to the wheels immediately and makes the vehicle prone to oversteering if not careful.
Was wondering if anyone else has noticed this in similar year models, and if there is any remedy. Have tried to back off the worm gear adjusting screw on steering gearbox but this just makes the steering sloppy. Is it possible to reduce the fluid pressures by 1. replacing pump pulley with smaller diameter 2. install pressure bypass or an orifice flow restrictor in the line between pump and gearbox 3. Any one know of TSB's/ fixes or other info from Ford on the issue.

Thanks
Dialtone

 

I looked and there arent any TSBs on this.
Replacing the P/S pulley with a smaller one will make the pressure higher but it wont really make any difference anyway. As long as the pump is turning at any speed faster than cranking you will have assist. On my race car I have played with pullies to get more power. The P/S pump turns very slowly and it still has lots of assist.
Have you had your wheel alignment checked? I think i would find a good alignment shop and have them bump up the caster as much as possible. This should make it want to go straighter on the highway and not be as touchy.