Type:
1998 XLT 2WD 3.0L EXT CAB 82000miles

Trying to diagnose a problem that I believe is the rack. With the front end in the air and the engine started and steering slowly either way, there is wobble/vibration that is visible and felt through both tires and the steering wheel. This does not occur with the engine off. Although, with it on the ground, the vibration/wobble is almost completely absent. The suspension should be fine, the control arms etc., inner and outter tie rods are good too, power steering pump is new.

My bet is the rack. Any opinions?

 

Can't really tell you if the rack is the cause of your issue, but unless it is physically cracked, I would hold out on messing with the rack and pinion. The aftermarket replacements are very low quality and almost always result in a loose feel to the steering. Definitely not worth the $200 replacement cost.