Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
You need to have this diagnosed quickly before irreparable engine damage occurs.
The LS V8 engines are known for oil pump pressure regulator valves sticking (generally partially open, and hence low or no oil pressure at low rpm/idling).
This won't be an easy fix, so you need to act before you need a new engine.
Sorry for disheartening news.
I hope you have had a chance to have your car looked at by a professional.
I hope my advice has been of assistance to you.
Have you had your car inspected as yet?
I would not drive the car in the condition as you have described.