I have a 1998 Silverado (5.7) and I noticed the temperature gauge this morning moved erratically (from around 160 to 230 or so). I searched and read of this happening upon changing a water pump, but I haven't had any work done recently. Any help would be greatly appreciated.

You could be haveing trouble with your thermostat or your coolant temp sensor.

try checking your water level first. mine used to do that when my coolant was low. changing the radiator solved the coolant loss for me.