Problem codes HELP

Hi i was getting the codes 1008, 0304, and now the MAF Code. I replaced the 1008 part but i'm stilling getting the code. Does anyone know any other methods i can do to check what else could be causing that problem? The 1008 is the Evap Canister Purge volume control valve.

I've checked the voltage on the Purge valve. Seems like good numbers. No negative numbers. The MAF as well show good numbers. Any ideas?

bumpy