Water on floorboard after rain

I have 98 Grand Marquis that gets water on the floorboard (mostly left rear) after a heavy rain. I ran a hose around everything and the only time I see water gurgling under the carpet is when water is run into the vent in front of the windshield. Has anyone experienced this and found a solution? Is this a common problem (I hope)?

Do you have a moon roof....? They have a drain to the rear on both sides that might have debris clogging the drain line.....

Can you take a photo & describe the problem area....?

I have the same problem with my 97 cv. Its on the right rear side, the dealer I purchased it from had a water Dr. fix it but its back, no moon roof.

Any one selling 16 inch cop wheels?