Oil pressure

Do you have stock oil gauge? Some of the factory gauges when they drop to 5-10 lbs. Of pressure won't register. Does your pressure come up when you are moving? Rule of thumb is #10's of pressure per 1000 rpm's. If you go up to 20-30 lbs. Driving on city streets and drop to zero at stoplight you could have a weak pump. Has it been a while since oil change? Filter getting dirty and full of grunge could give this reaction, too. But as far as changing the pump it's not too bad a job if you are a fair wrencher. You do have to drop oil pan to get to pump so there is your oil change at same time. Possibly have to take loose motor mount also if you can't get oil pan clear of the frame. If this started losing pressure over a short period of time watch for small metal shavings from bearings because worn crank and rod bearings will cause low oil pressure, also.
Could even just be gauge going bad, too. Good luck.