Sloppy steering

First of all be sure your tires are properly inflated; too high or too low can cause this.

Then get it aligned and the suspension inspected.

The first thing to do is to have the whole suspension inspected for warn parts and repair anything that is worn.

How is the alignment? Is it steering evenly when you steer to the extremes in both directions.

I had a 1994 33 foot PaceArrow with the 454 P chassis. I did everything to it because it wandered all over. Henderson super steer bell cranks and rear trac bar,got rid of the air bags in the front coil springs and installed henderson springs,inner and outer tie rods,idler arm,steering dampner,ipd large front sway bar with poly bushings on front and rear,Koni shocks,had steering box checked,two sets of tires over the years,a few front end alignments set to henderson specs then even more caster.
All this made a huge differance but still was a bear to drive and would like to switch lanes on its own. I finally fixed it.....I sold it and got a diesel pusher.

The screw on the steering box adjusts the gear lash. The gear lash is set when the gears are new. If the lash is now loose, it's because the gears have worn out. Screwing it in tighter will only finish wearing out the gears faster. If the gear lash is loose, replace the box with a rebuilt one.

Sometimes there is an adjustment screw on the steering box. My understanding is that you do this LAST, after making sure alignment and suspension are good, so you don't cover up a dangerous problem. Worked for me, after several tries (too tight, too loose, just right). Before you get an actual new steering box.

If you are not doing the work yourself, you need a mechanic who is willing to adjust it several times to get it good.

Too little front end caster can manifest itself as "loose steering" (and wandering) at highway speeds.

If you have a steering stabilizer shock absorber, replace it. It made a huge difference to a wandering steering wheel for me.

Bell crank or idle arms.