I had the same thing happen with my 2001 Dodge truck, different brand I know,but it relates. Running 70 mph crossed a bridge and thought the fenders were going to fly off, stuff in the cab flew all over.
Pulled over checked what I could found nothing missing. Decided to go to the next exit, much slower of course. Next bridge, same thing.
Anyway, made it to the next exit, looked truck over, checked tire pressure, all tires 15 pounds low. Aired tires up to proper pressure and have not had anymore problems,that was a couple years ago.turned out my pressure gauge was bad, that's why all tires were low.