Scotty I've put way too much money into this Truck ! But I have to fix it. I have replaced the purge valve and the purge vent valve, i checked the line going to the canister, it checks ok, I hooked up my scanner and the vent pressure seams low, it -.14. I had the canister out and check all lines they seem good. I did replace the gas cap with no luck! I don't know if I should buy a new whole Canister? The other issue is low efficiency on bank 2 cat. which I installed about a year a go. My short term fuel trim goes up and down from -2.0 to 1.0 my bank 1 is about the same. The o2 voltage looks like they are responding like they should. the Truck runs really good except the codes. and I live in New Jersey and need to pass inspection!! The truck just turn 100,000. Sorry I did not write Down the fault codes.