Tires and tire pressures was going to be my suggestion too. Is this tracking issue something that just started happening overnight on the same roads, or has it been a gradual change?

And along with tire pressures, a set of tires whose tread is getting lower and lower will sometimes have the same effect as they eventually become more like a set of slicks, which will tend to "track" like you're describing too.

If it's not the tires though, I'd agree that adjusting/tightening the steering box would be one of the first things to try.