sounds more like a blown shock. If it was a brake shoe, the steering wheel would likely shake bake and forth with the "grabbing" of hte shoe.
Also check ALL you suspension components for slop. Jack up the front end and give the everything a shake. Check for loose bearing, bad locking hub, loose lug nuts, tie rod ends, ball joints, shock bushings, etc. If you don't find anything I would stat be haveing the tires checked out and rebalanced (hopefully you bought them from a place that has lifetime balance to sacve money). It might be something as simple as you lost a wheel weight.
