Ses p0046

P0446 code has come up on the wife's 04 Suburban. It orginally came on last year and was fixed when I changed out the vent valve solenoid. It came back on a few weeks ago so I exchanged the vent solenoid under warranty. 2 days later the the code was back. Saw that the plastic hard line to Solenoid was a lil kinked, so I changed it to rubber hose from the evap canister to the solenoid. 2 days later the code was back. Changed the Purge valve, took off the evap canister to check if it was clogged. Evap canister was a lil dirty but was not clogged, was able to blow the dirt out of it. 2days later code was back, so I swapped out the gas cap. Again code came back. I'm almost at wits end with this. Any more ideas??:insane2: