This problem most likely is not your steering box. the usual culprits are: tie rod ends, balljoints, centerlink, or possibly the idler arm. The fact that you have uneven tire wear, and that it sometimes pulls you into traffic would suggest to me that it is something that is happening at one wheel but not the other. If you don't know what to look for, I would have the rod ends and ball joints inspected. If you have front brake problems as well, you might consider checking to make sure the wheel bearings are adjusted right.
Just food for thought.
Andy