The oil light comes on and flickers with raised RPMs then eventually stays on. What could cause this?

Have oil pressure checked with mechanical guage see if problem is pump or electrical like sender

Low oil pressure may be the issue. You need to have a manual test done first to confirm. If it is, then it may be more than just the pump as the bearings may be worn out causing the low pressure. A shop can make that determination for you and give you a bid.

Roy