My 1994 Chevy van developed a real bad shimmy a few months ago. I replaced the idler arm which was definitely bad but still drives like something is "out of round"? I changed both front tires and rims too. Could it be caused by a bad wheel bearing? It is much worse when braking but it occurs at all speeds. I'm thinking about getting a new rotor and bearings for the drivers side - that's where it feels like it is coming from. Just wondering if anyone else has had this problem. At this point it defintely feels unsafe to drive.