Steering wander

I've been having this issue of the steering being "loose" and have to correct it constantly. I have replaced all steering linkage and steering box, got it properly aligned. tires and wheel bearings are new as well. I did notice my van did not come with a front sway bar. I've thought about adding one but there are no threads in the frame where there should be for a sway bar.

Van listed above is a E-150.