Yes by all means clean the MAF sensor first. Don't remove it from the housing and don't be heavy handed with the cotton swab while cleaning the wire. If cleaning and/or replacing the MAF doesn't work you'll need to look for an intake air leak. When was the last time you checked the PCV hoses or replaced the PCV? When was the last time you replaced the UIM & LIM gaskets?
There's lots of repair info on the P0171 and P0174 DTCs.
