Hi Rich, I know we keep on about them, but are you sure the door membranes are good. They really do prevent the water that runs down the window glass from getting to the back of the doorcard (which is inside of the door rubbers)...
Also, check the door rubbers are good, and tight, especially at the lower part of the A pillars, there's a bit of trim that sits down there, lips behind the rubber...
These bits...
Any rain that runs along the wing as you drive, is pushed into the A post/Door gap and blown onto the rubber. If the rubber is even slightly raised, it'll get in, and drip down onto the carpet where these two pieces of trim are.
VBR
Ian