Why do I have such sloppy steering?

It may just be that you need to replace the steering box itself. Mine is sloppy on my 69 Dart and I got a tight one at a swap meet, have yet to install it... but I have it and it's tight. Yes, there is an adjustment as mentioned, but they don't last forever and getting sloppy is a sign that the box itself may be going bad. But take it to a reputable shop and let them check it out for you. YOu're not obligated to have the work done and a good shop will itemize what needs to be done for free or a small reasonable fee.