My own thought is with the cabin filter; the noise is almost at the firewall. I WON'T go to the dealer; they'll charge me two hours' labor to tell me what's NOT wrong. But I'll check the airbox and airbag again.
Let you know what shakes loose.
Black/tan early '98 Contour SE Sport; V6, MTX, loaded Kenwood KDC 316S CD deck; aux. dome light mod; trunk popper spring; resonator bypass; hood strut mod; SVT grille; Continental tires Mom also has black/tan '98 Mystique LS; V6, ATX, Alpine CD deck