i know a bad maf sensor will cause a surgeing, like your running out of fuel,try tappin the maf meter with a screwdriver handle, not real hard, if it's bad it will stall or run better or worse,i have also used a heat gun or hairdryer to find a problem/// sounds like yours is constant rich if so your o2 should set a code?
u can also test the maf with a frequency meter and the ford spec for it.