I have a GT with a sunroof, moonroof, whatever. Anyways I guess the 3 clips thy hold the back up are lost bc the back of the headliner is starting to sag. Funny thing is I just now notice it so I'm guessing they've been that way. Anyways I was wondering if someone had those plastic clips that hold it up.

And if your reading this, how can I clean the headliner without making it sour or smell bad.

try cleaning with just interior cleaner for the seats and such.
should work just fine.