I bought a 2007 Pilot with 20k miles on it 3 weeks ago from Honda dealer in Brandon, MS. It's been back for service 3 times since for shaking and vibrations with driving at low and high speeds. Pilot was a Certified Used vehicle with new tires. Dealer has balanced and rotated, test driven each time. After the 3rd time in, they said that they do feel the problem, can;t find any bulletins on it and don't know what to do. They even test drove other used pilots on the lot and experienced the same thing. What's going on here???