Why does my car pull to either side as if a strong gust of wind is pushing it while I'm driving?

When I'm driving there are random times where my car seems to tug to the left or right a little bit. It's nothing extreme, but more of a nuisance. A lil history on my cars condition - drivers side brake caliper has fallen off twice, my shocks need replaced, and I am due for new tires. Could it be an alignment issue, a balding tire, or something else?