Cant tell you about the sunroof trim.. but the headliner is, otherwise, held up by all the surrounding trim plus a couple clips, IIRC.
But that's just tedious.. not the hardest part.
The HARD part is that there's no quick spray'n'go fix. The foam medium between the hardboard and vinyl is failing and must be completely replaced. REPEAT; THERE ARE NO SHORTCUT FIXES
All the foam must be scraped off the board and the bits left on there fixed solid with a good NON-LATEX Primer.. Zinsser B.I.N {Lowes, etc} works well for that.
THEN you have to address scraping and fixing the foam on the vinyl, which is not so easy.. I only dealt with cloth and I scraped/rubbed then ran it through the washer, which makes a mess in the washer and you have to run a few loads of junk towels and stuff through to clear it out or your wife will be VERY upset.
I then got a piece of thin upholstery foam and used 3M 777 to first fix the foam on the board, then the cloth on the board/foam... LAST part VERY difficult and tricky.. and no, you can put the foam on the cloth first.
I suggest for 'finishing scraping', go to Lowes paint or tile dept.. look for a plastic 'scrubber' which looks kinda like a sponge but is more like a scratchless pots/pans scrubber, but large-celled
I suggest you scrape and prime the board, scrape the vinyl and then take it to a car upholstery shop.
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