If you tighten the backlash screw too much, the steering wheel won't center itself as you drive and it will be very touchy. Basically, it'll be all over the road as you try to find center. Trust me, it's not fun.
Try the adjustment screw first. It'll be a trial and error thing and it may take you a few trips around the block.
After you've tried the adjustment screw, if it's still too loose, then you'll have to start replacing parts. The good news is that you can rebuild the entire front end for fairly cheap. There have been a few topics about it here on the boards. You can get almost everything from NAPA Auto Parts or an auto parts distributor that sells Beck-Arnley parts. I think there's a couple places online too.
One or two things you might have to get from somewhere else. When I did mine, I couldn't get the the lower control arm bushings and the idler arm bushing. Since then, someone here on the message board has found both of those items. There's a post about it. I would try a search.
Typically in a front end rebuild you want to replace:
- Upper control arm bushings
- Lower control arm bushings
- Upper ball joints
- Lower ball joints
- Outer tie rod ends
- Inner tie rod ends
- Center link ends
- Any and all rubber bushings and seals
You may also want to replace the idler arm bushing and possibly rebuild the steering box, depending upon how much wear your components have.
When I did mine I took the opportunity to replace the front wheel bearings too.
And, of course, once you get it all back together you'll have to have it aligned.