Why does my oil pressure light keep flickering?

I drive a 95 chevy cavalier. My oil pressure light, the little lamp (I'm assuming that's what it is because I also have a check oil light) flickers on and off every 5 seconds when I am idling. I recently changed my oil. I also fixed a leak in the power steering pump and replaced the fuel pump and the alternator, both of which needed repairs for a few months. It is only when I come to a stop that it does this, and I drive a long distance every day. It is very consistent every 5 seconds. Any ideas? Thanks