Obvious first check is if the wheels are still correctly balanced. If they tossed a weight or they are wearing unevenly, the balance would be off and that would also produce your condition.
If that is not it, I would get into the Ford shop soon and have them find and fix the problem while you are still under full warranty. If your 3 year period is coming to a close, get them to do a full check of the car and get paperwork started on any complaints you have and anything they can find. That way it will still be covered, even if they do not get to it while you are still in the coverage period. I did that with mine and they replaced a pile of things just to clean up stuff, all no cost.
pax
smn
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'98, Black
Mod.Porter intake, K&N panel, SARC cutout, instrumentation cluster, 23mm rear swaybar, 245x50x16 Bridgestone Potenzas