Have you tried rotating the tires to see if it makes any difference?
What shape are the radius arm bushings in?  Wheel bearings reasonably
well adjusted?  Overall condition of the front suspension?  You said
the air pressure was per spec but what spec is that?  Whatever it is,
try a higher or lower pressure and see if it makes any difference.
Also what about wheel alignment?  The one thing that has made the
biggest different on my 92 has been tires.  But since you already have
Michelins, unless you just happened to get  a bad one or two of them
it seems unlikely it's your tires. Another thing to look at is shocks.
There really is no good answer - when this problem surfaced years ago
Ford tried to find that "good answer" and never could and finally gave
up.
--
Elbridge Gerry, of Massachusetts:

"What, sir, is the use of militia?  It is to prevent the
establishment of a standing army, the bane of liberty.  . .
Whenever Government means to invade the rights and liberties of
the people, they always attempt to destroy the militia, in order
to raise a standing army upon its ruins."  -- Debate, U.S.  House
of Representatives, August 17, 1789