[red99]

I've parked on my driveway where the front is at least 6" higher than the rear with no problems. I am always careful to remove any debris from under the cowl as soon as I notice it. To keep the cowl clean I use a piece of 1/2" vinyl tubing stuck into the hose of a small shop-vac. Seal around the tubing so there is suction on the hose. The hose is small enough to reach through the openings in the cowl and suck up or pull out the pieces of debris.

Also, like jfoj says, remove both sides of the dashboard covers and remove all the debris you will find there. One side covers the cabin air filter, the other side the ECU.

 

[red99]

That box under the ? is the ECU. I think it is just a solid panel underneath it.

Did you remove the windshield wipers and cowl cover and clean under there as well? That is where the little dams can happen that will send water into the cabin. If you did clean that, then maybe it is the seal around the windshield that is leaking.