The Dreaded P0440 code need some help

Hey guys I'm in need of a little assistance. My 2002 V6 Tacoma Prerunner has been throwing a P0440 code and the occasional P0442. I also did get an fuel smell sometimes after existing the truck after driving. I've been ignoring it for about a year but I got to get and emission test in 2 months so time to take care of it.
I've bought a new gas cap from the dealer and visual inspected the hoses that I can see. Cleared the code. It came back a few days later.
Took it to a mechanic to get it smoke tested, no smoke coming out and it held pressure. He did say the vent valve did not go on and off with the scanner. And recommended changing the charcoal canister. We did also find a small leak on top of the gas tank where I believe where the fuel cut off valve is. (This is what might be causing the fuel smell.) So I'm about to go buy a new canister cut off valve and gasket. Hopefully this will solve the problem.
So my question to you all is there any other possible reason for the code showing up. I'm hoping to clear this code once and for all.
Thanks for reading this and any input will be appreciated.