any tips on cleaning out the cowl?

Ouch! I would have removed the heater box and left air box and reached up through the hole and scooped/blown/rinsed/vacuumed that stuff out. I've seen a lot of similar stuff here with all the pine needles and mold - turning to mulch.

There are caps on each side of the cowl in the hood hinge area where they drain make sure they are not packed with debris.