I get a lot of questions from people who are sick of how their Ford steers while the wheel is in the center. Usually you have to constantly correct the vehicle to maintain a straight line. A lot of slop and looseness develops when the steering wheel is in the center.
One thing you do not want to do is tighten the adjustment screw on your gearbox. Tightening the steering gearbox on a Ford will get rid of some of the excessive clearance while the wheel is straight. The center of the worm drive is where most of the wear happens. That's where most of your driving occurs, that's where your wheel is when you hit those pot holes and bumps in the road. The problem is the other parts of the gear are not worn as much. Now after you tighten the gearbox, the clearance is insufficient while the wheel is turned.
This insufficient clearance causes excessive binding in the steering gear. When you turn the wheel, it will get harder to turn and you will lose some of all of your steering returnability. Now every time you turn, you have to pull the wheel back straight again with the same amount of effort it took to turn the wheel in the first place. Normally, the effect is easy and almost automatic because of the caster built into the alignment.
I've loaded a video up on YouTube showing this exact effect.... https://youtu.be/nkM029Spwtg