Mass air flow sensor and gauges?

I have a 01 ranger 4X4 4.0L I hear a like a bogging sound when it idels it happens every 10-20 sec. I have some starting problems also but waiting for money to fix whatever it is fuel pump or fuel injector. I want to know when the mass air fuel flow sensor goes bad I have been getting real bad gas milage too. How hard is it to put white face gauges in my ranger I kinda had it apart and it seems like the plastic peice is glued down. Well if any thing of this makes sence please reply!