Evap code p0455, or p0442 or p0456?

Hello, thats where I would start since you are showing Large(gross) leak and small leak codes. Take the Purge valve off and see if you can blow air threw it. It should be sealed when its off. You can tap the Purge valve lightly and look for any charcoal bits from the canister. Peices of a charcoal canister breaking up can cause particles to end up in the Evap lines and eventually the Purge valve.
If it turns out not to be the purge valve, you will need to go about testing for an Evap leak. With a scan tool you should be able to close the vent valve and purge, then monitor the fuel tank pressure sensor, when you turn the vehicle off the pressure should start to rise in the fuel tank. Evap leaks can be one of the most difficult diags to do. Ill post a diagram of the Purge location, but Im sure you already know where it is.

Here some service info on the P0455 code and the Purge valve location. The Purge valves can stick too, working one minute then stuck the next. So dont let it trick you.