Possibly:
- low oil level; add half a quart of oil and see if things improve
- sludge in the oil pan being sucked up when the engine revs up; you'll only get that out by removing the pan; looking inside the valve cover to see if there is sludge in the head area would be an easy first step to determine if this is a likely issue
- bad or plugged oil filter blocking flow; replace with a WIX oil filter and see if that helps
- bare oil pressure sender wire moving against the block or other metal surface and grounding the wire and lighting the light