If you are still using the O.E.M. steering box,there is a high probability the box is worn out! Those were made to have lubrication in the box,in all the years I have worked on tri five cars I may have only seen that a few times at best. Take the linkage loose from the pitman arm and see if you can feel any binding.

if its power steering the control valve could be gowing bad or a line could br pinched . .manual camber and caster need checking .