I have a 2000 Pontiac Grand prix gtp. Yesterday it has started this cutting out problem, it only cuts out for a second then takes off, has no problems at high rpms just low ones. I have one code showing up and its for the rear o2 sensor..the one in the u-bend. the code will not erase just comes right back on when you start the car. I was told the cutting out problem was something other than the o2 possibly being bad, so my friend told me to unhook the mass air flow sensor while its running and see how it acted. It raised the rpms slighty while idling and now no longer cuts out. runs good now..i have no idea what could be the problem and if some how these problems are connected? Also before unhooking the Mass air flow it idled good but once or twice a minute it would stutter and almost die. I have no idea whats going on so any help would be great! thanks.