[asphaltgambler]

Note worthy advice from above. If the issue remains after that and certainly that is the easiest thing to do at this point...........................plan on pulling the pan for a visual inspection.

Typically a clogged or partially clogged oil pump pickup screen will do just the opposite - where you'll have adequate oil pressure at low RPM's but volume / pressure will fall off when driving.

If you pull the pan and no obvious signs of screen clogs, pull a main bearing cap preferably towards the front away from the pump. Most likely you'll find you have excessive clearance in the main and rod bearings.