1997 Ford Windstar Bad vibrations/wobbles!

Any free-play in any of the joints can cause shudder / vibration. If the wheel rotation, vehicle speed, and free-play enters the correct vibrational harmonic, it can shake as you describe. There's lots of physics to describe with rotating and moving parts. I'll leave out the details.

Ever throw a Frizbee in a less-than-perfect mannar and you see it fly through the air wobbling and veering off to the side? Same concept.

I know you specifically mentioned outer tie rods. Check for free play to the inner ones as well. Jack up the front end and try to move the wheels right to left. Have an assistant look at the rack-n-pinion for any play on the inner rods.

If there is free play in the ball joint, you're best off replacing it.

Finally, if your vibrations occur mostly during braking, your brake rotors are likely out of true. If there is enough material, get them machined. If not, replace them. Be sure to do the rotors in pairs: I've learned the hard way that just fixing one side comes back to haunt you in the future.

A bad wheel bearing will make a grumbling, crunchy noise at all times, depending on how bad condition it is. Bad wheel bearings can sometimes be detected by two ways:

Jack the front of car up SECURELY, follow all safety stuff like jack stands, apply the emergency brake, etc. Run engine at idle and put gearshift in Drive. It's a front wheel drive, so front wheels will begin to spin. Carefully grasp coil spring with your hand. If you feel a lot of vibration, the bearing is likely damaged. Coil springs amplify the vibration, making the diagnostics easier to detect. Shut engine off. Grasp wheel from top and bottom. Try shaking it, pull and push wheel. If there is any free play, bearing is likely damaged.

It's a wheel hub bearing assembly with roller bearings. The hub bearing can be pressed out and replaced (re-use the hub). Beware though: there are two types of bearings: The cheaper ball-bearing type or roller-bearing. If you plan to keep the car, go with the more expensive roller bearing.
For example, AutoZone sells a "Valucraft #V49" ball bearing for about $20. AutoZone also sells a roller-bearing "Timken Set 49" for about $32. Do yourself a favor and get the Timken brand. The ball-bearing type simply is not as durable and you'll likely end up changing it again in the near future.

Wheel bearings take a lot of abuse, so unless the front tire was vibrating so violently that it damaged the bearing, I would more likely suspect the problem is the tie rod.

Again, look at the wheel again with an assistant and see what part(s) are loose. You already replaced the outer tie rods, so if the inner tie rods are loose, you'll see the free-play as you push the tire from side to side. Maybe have a third assistant holding the steering wheel to eliminate that factor.

If the tie rods are tight, you still might need to replace the ball joint, as you mentioned it has free play.

Try the vibration test, and listen for a constant howling or grinding which would be a bad bearing.

Yes, an unequal tire (or one with a bubble in it) can wreack havoc on front ends. My experience: first to go are the tie rods, then the ball joints, and wheel bearings seem to be most durable. Unless high mileage and dried-out grease within caused them to fail.

Good luck.