Have you talked to any of the folks who do auto headliners? I'm assuming it is the glued up foam backed type stuff. That kind of headliner will just keep coming down as it is the foam backing that has "died". I recently had mine on the Jeep (1995) replaced. I think the foam backed headline simply dies after 9 or 10 years (depending on the amount od heat it gets). You basic choices will probably either replace with the same (pro job and do it again in 10 yrs) or tear it out yourself and replace with some other material. A pro shop could also replace with something else (like vinyl or that "carpet" like stuff).