Lincoln Repair Questions? Ask a Mechanic for Answers ASAP
There are quite a few things that can cause a shake while driving at high speeds. Alignment issues, tire balance issues, suspension issues, steering rack, bent wheels. This will be hard to diagnose over this site. You may have to bring this in to a shop.
Lift up the front of the vehicle, shake down the front wheels. side to side and top to bottom. feel for any looseness in the wheels. Look for loose ball joints, tie rod ends, wheel bearings. Look at the tire wear, check for uneven high and low spots on the tire.