I have a leak on my 03 F-130. A big enough leak that it filled up the channel above the rocker panel where the wiring passes to the rear of the cab under the floormat. Further inspection has revealed the water appears to be coming through the firewall just above the passenger side floormat. There is a plastic piece that looks like it passes through the firewall on the left side of the passenger floor pan possibly going to the fresh air plenum. This piece has a foam gasket around it that is sopping wet. Has anyone else experienced this problem? The truck has never seen mud so I assume nothings clogged.

Thanks for any light you can shed.