Passenger door hangs down too low to shut

It sounds like you need to adjust the hinges. If its been this way for a long time and it sags alot, then the hinges are worn. It needs new hinges.

Get a hinge rebuild kit from any mustang vendor. They are cheap.

Hopefully the bushings aren't so shot that the pin has been wallowing out the holes in the hinges; or then you're lookong at replacement hinges. Most repro door hinges are about the same'quality' (using the term loosely) as repro hood hinges; so you'd be better off getting good used ones.

Don't know what year your Stang is; but I've heard that somebody was "rebuilding" old door hinges ffor the 67-68's. He bores out the holes in the hinges' "door side"; welds in a thickwall tube, the bushings, then smaller diameter thickwall tube with a grease zerk in place of the solid pin. That way you can lube the bronze bushings with something that lasts longer than a squirt of silicone spray.

I don't know which Mustang vendor(s) might be selling them; I've only heard about them from one of the Cougar parts vendors - they used the same hinges as the Mustangs 67-73.

Now if only somebody would do something like that for hood hinges - especially for the huge hoods of the 71-2-3's !