Gummout or any other choke/carb cleaner. This is for metal valves only. Ford used plastic on other cars, and my buddy melted the one off his T-Bird Supercoupe. I also separate the electric motor part from the valve by removing the two screws, and then I go to town on the valve with Gummout. I don't brush it out, but I do reach inside with some needlenose pliers and grab the shaft that runs through the thing, and work it around to make sure that the Gummout is getting to the area between the sides of the valve where the air flows. While the Gummout is soaking I also swab out the recess in the electric motor out where the shaft seats, and put a tiny dab of dielectric grease in there. Then I shake the Gummout out of the valve, put it all back together and fire it up. Also be sure to take a close look at the gasket, since the heat from the EGR valve makes them brittle, and they'll eventually crack. A new gasket is not a bad thing in any event.