I have a 1993 Camry LE 4 cyl..

Here's what I did to clean the EGR Valve throughly...mine is the original and has 260K on it..

-with the EGR removed from the car and the bottom exhaust pipe removed, and all carbon deposits removed from the EGR valve opening

take about 7 pipe cleaners and twist them all together to make one big "twist" pipe cleaner. (same thing like splicing a wire and twisting the exposed end togother)

take a clean vacuum hose about 1 foot long and connect to the top vacuum line of the EGR.

spray the end of the "twist" with carb cleaner and insert through the bottom end of EGR valve.

While continuing sucking on the clean vacuum line, it moves the piston up so you can push the carb-cleaner sprayed "twist" up the bottom end and around the piston and twist it back and forth to clean all around it. the "twisty" begins to fray like a toothbrush around the piston to clean the piston and the seat thoroughly.

repeat the method with the other end of the "twist" to make sure all is cleaned.

test the EGR to make sure all is cleaned by blowing through the bottom end of the EGR like a trumpet. if cleaned properly, no matter how much you blow through the end, no air will pass through the seat/piston. ( the "man vs. wild" method)

4 minutes later, you're ready to re-install the EGR back on the car...

hope this helps..