check this quickly at home, jack the van up and check for play in the wheels from back to front and then up and down, just checking if the track rod ends and bearings are giving any play, with wheel bearings you can get faulty ones (especially if they were cheep ones used) also look at the rubber cv boot) if you can only do this while the van is jacked up put an axle stand under first if you can see grease escaping from the boot, that need replacing.
wheel bearing could cause play from the top to the bottom, normally they humm while driving but not always