Loose could be from several things, from a rag joint that's on it's last legs to a box that's got excessive slop.
As mentioned the wheel was not centered prior to adjusting the tie rods. Tightening up the steering box adjustment has never worked for me on any vehicle I have tried it on, it usually resulted in stiff spots because the box was junk. Your mileage may vary.... but it may be best to swap it out for another unit.
Unless you had a fancy Snap-on puller, you would have had to pull the box to change the pitman arm. ( 4x4 )
It's pretty impossible to diagnose something over the internet, just going by what you say.