My car shakes when i get to 55mph or higher and shakes when i brake to stop

Distance= 503 miles.

503 ÷ 55 = 9.145 hours.

Now this is IF you could maintain 55 mph constantly AND didn't have ANY stops, i.e. fuel, bathroom, food, etc.

Hope this helps.

A bad rotor would only cause a shake when you are using the brakes. A bad tire could shake at 55mph and above.
I would get a second opinion to make sure.
The shop could rotate the tires and see if the vibration moves to a different area of the car.

Struts

sounds like emergency brake stuck on ..does the car roll or do you smell hot brakes

1. out of balance tire because it sounds speed spacific.
2. worst of all! Loose lug nuts or possibly loose spindle nut. (you will need to lift the wheel off the ground to tell)
3. worn linkages i.e. ball joints, steering linkage, anything that would allow play in the front wheels.

sounds like to problems did you actually hit some thing? if not the burnt smell should go away. about the bounce at 45 mph are you sure that it's not a shake and does it go away at 55 mph or different speed? if this is whats happening the front tire is out of balance weight could have fallen off. try this

more than likely you need to have your brake rotors resurfaced or replaced

I have several comments. Because you mentioned 55MPH, this is a "cam phaser" engine and the part called a "cam phaser" stops affecting the engine from about 1200rpm to 2000rpm. The bad effects cause engine shaking and rough drive-train effects and when you stop the truck it will run smooth again.

The ideal test would be for you to coast at 55mph or when the shaking starts and go downhill to maintain speed. By putting the truck into neutral, you eliminate the motor problem and if the problem persists it is a tire, brake, or suspension problem.

You can have play in the tie-rod ends. I have noticed with Ford brakes that overnight rust can cause parallel rust spots where the brake pad contacts the rotor while the truck is parked. Until these rust mounds wear off, the shaking can be worse if the rust spots run parallel to each side. Some brake material is worse than others to cause this problem.

Bad belts or bent rims can magnify when both tires hit their low spots at the same time. You do have a spare which could be put on the front one at a time to see if you can find the bad wheel.

Bad hub bearings can cause this problem. Check for recalls. We had a leased Explorer with under 10,000 miles and it needed both hubs replaced for defects. You indicate you have less than 36,000 miles, a warranty threshold.

I have the same problem, you need to change de oil transmission or try an additive for aut. trans that resolve the problem for a while, but is almost most better changing de oil.