1995 Ford F-150 Low oil pressure at warm idle

Did you hook up a mechanical guage to the system? The stock guage is only an idiot light wired through a swinging needle. The only thing the system is able to tell you is that you have at least 7psi of oil pressure. It's not designed to tell you actual pressure.

You can have low pressure (making sure to measure with an accurate mechanical guage) if the oil pump pickup is partially plugged, worn out oil pump or the crank or cam bearings are worn out, though camshaft bearings rarely ever wear out.