in the evap there is a pressure sensor, vent valve, purge solenoid, canister. there is also 10+ codes.
by your description though it seems either your canister is clogged or your vent valve is sticking shut. the last being the most common. i havent worked on a 07 but most you can blow out the filter take apart the housing and shoot the solenoid with wd40 and use a battery to actuate it a few times. if it wont move or seal then you need a new one