check tires to see if they might be rubbing? or jack up front end and put it on jackstands and have someone move the steering wheel while you watch the movements...may have something in the way, or could be bad tie rod end or in the pitman arm... could even be the king pin bushing..
My truck ended up getting 2 new tie rod ends when I serviced the axles when I had to beat them out of the arms... It turns alot better now ... I also cleaned the king pins and cleaned out the zerk holes... if you have trash on the zerk when you put grease gun on it it just pushes dirt into the bushing area or on the bolt to be lubed and can foul it up if it is enough trash....
But like I said, start by putting her up on some stands and start trouble shooting... check the travels and listen for and signs of possible trouble... you can then disconnect each wheel from the tie rod and check each wheel seperate to isolate the king pins or if it is the tie rod ends.. I can tell you that I didnt want to replace my tie rod ends but ended up anyway when I damaged them trying to get them apart... $100 bucks each....
Post up what you find..
could even be in the steering box...