My black '90 GXE came with a factory spoiler. I like it, but the surface is all dull and cracked from sun exposure. Is there anything I can do? The sirface seems to be soem type of plastic coated rubbery material. Could I just sand, prime, and spray it with touchup paint? Or is there some type of dye I should use?

 

vinyl conditioner doesn't make it look dark / even?

 

If your factory spoiler is faded and CRACKED, you should remove it and spray bomb it yourself or take it to a bodyshop (probably better). Proper prep and maybe even stripping it is a good idea.

It should come off by unbolting it from the underside of the trunk lid. I think there was a thread in the 3rd Gen section about spoiler removal not too long ago...

 

Afraid Bman's correct. Your clearcoat and paint are damaged beyond what a polish or rubbing compound can reverse. Your best bet is to get it repainted.