The cowl vent by the windshield wipers drains thru the rockers under the doors. Under the doors there is a pinch weld that runs from the front wheel to the back wheel. There are 4 or 5 little 1-2 inch by 1/8 inch slits in the bottom of these. Take a piece of coat hanger and try to pull the leaves and such out. Pour some hot water in the cowl vent and see if it drain or runs in the car. Windshield or ac drain could also be the source, but most likely it's the cowl vent and drains. Good luck Brian