The rear end of the car started swaying on me like it were a rwd car going into a drift. At first it started happening at high speeds only around corners but in only 4 days the problem started to occur at 25mph on straight stretches with every dip and bump in the road. The rear will sway left to right while the front drives straight. Is this a lower control arm issue? Should I replace my upper and lower control arms together?
Don't start throwing random parts at the problem until they're diagnosed as worn out. With every suspension part you replace, the car will not handle properly until it is aligned. Ford already has way too much trouble with miserable tire wear even when the alignment is correct.
The cause could be as simple as a loose or worn wheel bearing or as serious as a broken suspension arm due to rust. The best is to have the steering and suspension systems inspected at a tire and alignment shop. Ford front-wheel-drive cars should be inspected at least once a year and immediately when you start hearing clunks or squeaks. They have more trouble with worn parts leading to loss of control and crashes than all other manufacturers combined. Swaying is another symptom that must not be ignored.