I noticed a little bit of water in my spare tire well so I pulled out the trunk trim and found that water was coming in from the outer tail light mounting holes. There are two square push-in fasteners that screws go into. The water leaks in from those openings. I tried changing out the little thin rubber gaskets under the push-in fasteners but it still leaks.

Does anyone have any similar experiences/solutions?

 

This is on the evo, or your lancer ES?

 

there's a foam gasket behind the tail light, make sure that's intake. You can put some gasket maker stuff (RTV) on the tail light tab in the area where the two screw holes are so it seals the wholes. Alternately, you could put a rubber washer behind the screws as well.

 

I think your blinker fluid is leaking. must take it in to service ASAP before you run out.