At first I thought my vent solenoid was toast but now I'm not so sure. I've already replaced my evap solenoid on the engine so I know that's not my issue.
The car seems to run fine, it's not running in limp mode and still is pulling 15lbs of boost.
It has 119k miles.

 

Sounds like either one of the tubes is broken or obstructed, or the evap purge vent (under the gas tank) is broken.

 

I got under the car and inspected everything and all looked good

 

Then the purge vent is bad or the tank seals may be bad.

Did you have the codes cleared? Did they come back on? The OBDII EVAP test is very weird.

 

I did have the codes cleared and it came back on couple days later, same codes.

 

I've replaced the evap solenoid and the harness and I got the check gas cap notification this morning when I came to a complete stop

 

AH HA, That's when my LT did it. Turns out it has nothing to do with my EVAP system, it was a mucked up O2 sensor. When the 2 O2 sensors agree with each other exactly you get a code thrown, that happens sometimes when you remove your foot from the gas pedal quickly.

In my case, a seafoam induction and oil treatment fixed it until I finally got the EVAP test to run. Then I replaced my post O2 sensor. My problem seems to have come from a stuck piston ring causing a quart of oil to burn in 1,000 miles gumming up the cat and sensors.

Yours could be just a vac leak under the hood.

Another instance of codes not meaning what they seem to say.

YMMV

 

I did a smoke test and they found no leak. But indeed my check gas cap only comes on when I have been sitting at a stand still

 

I have heard that SS has a PCV valve, could be a cause.