I have a 2001 monte carlo ss keeps showing low oil pressure and they guage is going back and forth I have the right amount of oil in the engine

Could be a bad sending unit (sensor) casing the problem, or maybe something else:
You say that the "gauge is gong back and forth" when is this happening? At idle, then I would suspect the sensor. But other items might be the oil pump pressure regulator or a cracked pick-up tube, not likely, but possible.
Now if the gauge pressure is fluctuating while driving, there could be a host of problems such as: oil pump or main bearings wear or some internal leak.
The best test at this stage would be to connect a manual oil pressure gauge to the engine to see what exact oil pressure is reading.
Don't drive the car until you get this fixed. You could turn a small problem into a big one if the engine truly is not getting oil. A cheap repair could go to 3-4 grand if you fry the bearings in the engine.
Comment back with your mileage and further description of the problem if you want more help.
J (Working on Small Blocks since 1967)
(2.21.2011 00:42 PST)

Replace the oil sending unit (pressure switch) Before doing so, check to make sure wire connected to it is tight. A loose wire can produce same symptoms.