outer and possibly inner tie rod ends.
I just fixed this exact problem on my 97 Mountaineer.
Both my outer tie rod ends were dried out and worn rough and were squeeking and transmitting vibration through my brake pedal and steering wheel.
I replaced them with Moog parts for about 74$ shipped from rockauto.com.
Now i have a squeek still, from my shocks, but NO MORE feeling vibrations and loud racket.
To test yours, jack the front end up and support on jack stands.
Unlock the steering wheel so you can move the wheels left to right manually.
Grab hold of the outer tie rod end shaft and have a helper turn the wheel from lock to lock or turn it yourself and feel for the vibration to travel through the tie rod end to your hand. If y ou feel that vibration and hear it there, you can bet yours are just like mine were, dry as a bone and worn out.
I got 140k miles out of those stockers, so i am pretty happy with those parts. Im sure the Moog parts will do me just as well.
GL