when I turn my 92 firebird lo3 the oil pres is about 30 (half way on gauge) or a little higher but the with in about 20 min of idealing of 3 blockes of driving i start to lose pres all the way down to the zero mark but it only does it when i stop at a sign or traffic and then goes back up till i stop then down to zero
so can any one help i have no idea oil pump or sensor and if pump is there a ez way to replace other then pulling the engine.

 

Pump will either work or not. Very rarely will a pump itself fail.

First, check the oil level. If it's too low, the pan is being sucked dry.

There is a possibility that the pump pickup fell off and when the engine starts to get oil up top, the level in the pan has dropped below the level of the pump.

Install a mechanical oil pressure gauge and confirm that you are actually losing pressure.

Changing a pump or reinstalling a pickup tube requires pulling the oil pan. Not something that's easy to do in a third gen without lifting the engine.

 

but , first i would change the oil press. sensor . i think that is your problem . good luck .