major vibration problem after driving 65mph for 10 - 20 minutes

You have got to determine if its powertrain related or wheel/tire related. A break down in the ignition could cause a vibration but should set a Check Engine Light. A professional scan tool can be useful in diagnosing engine or transmission problems. It hard to guess without being able to experience this problem first hand. Can you tell what area of the car vibrates , front/rear left/ right? Try rotating the tires and see if the vibration changes. Can you feel it in the steering wheel or is it more the whole truck vibrates?

I had the same thing happen to me. I took it to a toyota dealership they wanted chage me 1200 rip it apart. I ended up googling my issue and it turned out to be my front throttle it was hanging from a thread. Look at that.