I am getting 442 and 456 codes on my 2003 JX8 Sport with 58K miles. I burnished the fuel filler neck surface with steel wool and applied a thin layer of axle grease to the fuel filler gasket. I also added a layer of electrical tape to the back of the gasket to make it thicker for a better seal. Cleared the codes and CEL came on in 2 days.

I installed a new evap canister purge valve and reset the CEL codes and in 2 days the CEL was on again. Same codes.

What should I do next to fix this problem?