Before I gave up and reupholstered them, I sprayed them with some fabric paint; it didn't work. By then, the loose fabric pieces were turning into dust. Maybe, just maybe, you could try brushing on some quick dry polyurethane to temporarily seal the surface.
--2005 F350 Superduty Crewcab, 6.0, 4wd, short bed, 3.73 gears;
--2016 Montana 3711FL, 40'
--2014 Wildcat 327CK, 38' SOLD