Hi, there
 I have a Sienna Toyota van (Year 2000).  It was all fine and ran well on freeway. A couple of months ago, I got grinding noise when I apply the brake.  So I took it to a mechanics shop, “Firestone Complete Auto Care Store”.  They found quite a few problems with the brake system.  As a result, the rotors, drums, brake pads, braks shoes and calipers are all replaced.  After that service, whenever I drive the van on freeway, I got bad vibration whenever I drove it to about 65 MPH. I took it back to the same shop.  They did alignment, balance and rotate the tires.  Still, I got the same bad vibration.  Last weekends, following the shop’s suggestion, I had them replaced all four tires.  Well, after that, I still got the same bad vibration.  Seems to be the shop ran out of ideas.
 What it could be wrong?
 Thank you very much.
 Xuelong