steering goes stiff then normal, 95 jeep wrangler?

[random]

does this mean my power steering pump is going, my dad looked at everything mechanically and said its fine, he replaced the universal on the drivers side,but that was the only thing bad, the steering will go normal then stiff, then normal and stiff again, like u never know when its gonna become stiff, i dont know if that makes sense lol, basically it feels fine, then it will feel like ive lost powersteering fluid or the pumps broke, i think the pumps going, but im not a mechanic so i wouldnt know lol, plz help, im gonna have my dad look at it this weekend but would like to know something before hand, also is it bad to drive it like this, it could also be the steering knuckle right, idk if it is tho cause my dad looked at all that since he replaced the universal