oil pressure gauage bottoms out

Ok I have an 83 944 5 speed. Sometimes when I am driving down the road the oil pressure guage just bottoms out. It will make a funny noise and start knocking when it does this. Does it mean that the oil pump is going out or what?

Well, can you isolate when it happens?

So stupid but did you check the oil level?
Try running an extra 1/2 quart of oil

Other things
Oil pickup tube may be coming off.
OPRV may stick open.

LOL that was the first thing i did was check the oil. I even thought maybe it was the oil i was using so i changed to the 20/50 thinking maybe it needed a thicker oil. I will check those other things and let ya know if it helps. Thanks for helping me