1997 Oldsmobile Cutlass oil pump

Engine Mechanical problem
1997 Oldsmobile Cutlass Automatic 163000 miles

when driving my car will stop running and it willl usually start back up, but I have to pump it. My throttle is sticking I been told. Thought it was bad gas or water in gas. So I put heet in it. It stalled on me and had to tow it. I was told it was oil pump not getting pressure. Would that go out like that? Should I get another person to look at it. How much is an oil pump? Thxs.