You gots meeces is what... Little rodent friends making nests in your HVAC system. I have had pretty good luck using a screwdriver to gently pop out the vent grates and I think yours are the same as mine.
In any case you might try your local major hardware chain and look for a kit they sell that adapts a regular shop vac hose to small cleaning attachments. It might allow you to get in there and vacuum some of that nesting material out of there.
A cheapo, rigged alternative might be to duct tape a smaller diameter hose to the end of a shop vac and use that to get in there after removing the vent.
Mike: 1997 SE w/ 183K, aka White Horse
, Gutted Airbox w/K&N, drilled 180* t-stat, tint all around, clear corners w/SilverStars, "PONTIAC" light up tail, PEMs, NGK TR55s