Not sure how to do it on the cougar but both of my jeeps have done this. It is an easy fix. You need to find where the water is coming from, tap through the plastic it should be under the carpet up near the top of the carpet tap it in the front near the bottom. A lot of water will drain out of there, have something to catch all the water with. get a metal clothes hanger or something else long and thin feel around inside that area along the back wall near the bottom you will find the drain hole push the clothes hanger or what ever you use into that hole until it wont go anymore, what ever is clogging the hole should move pretty easily, your mainly just breaking everything up inside the drain tube. once you do this you should be good, take a bolt a piece of plastic or what ever and cover the hole back up so that it wont leak since that whole area fills up with water. i used a bolt each time I have done this and screwed it down nice and tight, and then put some sort of water proof sealant around it. Like I said I'm not sure if it will work on the cougar but it worked in both my jeeps and I got that from a tech at the jeep dealership. I wouldn't go drilling into plastic piece with out knowing what was behind them first.