frustrating P0446 code

[Old Bay]

2006 5.3L automatic 4x4 crew cab 1500

 

P0446

I'm due for emissions in my state in late June.

So far I have:

Cleaned the evap breather filter 
Replaced the evap canister solenoid 
Ran it for several days same code popped back up

Next round:

New gas cap (old one's o-ring was all cracked up
New evap purge valve on engine.

So as far as I know what is left of the EVAP system is the charcoal canister, the pressure sensor on top of the gas tank and possibly a cracked evap line?

Is there something I'm missing or over looking?

Also if the charcoal canister is the most likely culprit it seems rock auto has one for $63 while the local parts store is almost $200.  Is there really any difference in them?

[davester]

charm.li (website) has the vehicle-specific diagnostic procedure for that code, you can use to find what the cause of it is.

[richard wysong]

If you Google the code there are a few Utube vids on diagnosing the code