Emissions Control Valve Fault

I have a 99 Silverado 1500 5.3L 4WD and the check engine light is on. I have retrieved codes from the computer and it had the following: P0102, P0443, and P0449. The first refers to the Mass Air Flow sensor which I have repleced. The light is still on. The other two refer to the Evap Emissions Control Valve or purge malfuction. Does anyone know what this means or where under the hood is this device? Could there be some other reason?

Evap has to do with your fuel tank. If the fuel cap is leaking or any of the lines are leaking it is probably going to give you that purge valve code. Or, it could be the purge valve, it is probably located somewhere around the fuel tank. I work at Ford so Im not really familiar with Chevy stuff. Good luck.