2001 Ford Escape Running ROUGH / literally shaking the car

Not for certain, but the coil packs used on each spark plug tend to fail on these vehicles. This causes a misfire (your symptom). If the misfire is bad enough it can cause a rich condition which can overload and melt your cats.

If it has generated a code (check engine light) take it to an auto parts store and see if they will help you read your codes. If it is indeed a misfire, you can pinpoint the cylinder that is misfiring, replace the coil pack (or packs) and it will likely solve your problem.

The coil packs are about 65 bucks aftermarket. Cylinders 4, 5, and 6 are in the fron and easy to change, but 1, 2, and 3 are under the intake planum in the back and you must remove it to change them out. I hope this helps.