1994 tempo oil light on at low RPMs

I got a 1994 Tempo with 79000 miles. It set for about 3 years but was running with it was parked. Started driving it again changes spark plugs and spark plug wires. I was coming home Saturday and it died and the oil light came on. I let it set for a few mins then started and drove it home about 1/8 mile away. It was making a rattling sound in the tappin cover. I changed the oil and filter and the noise stopped but the oil light came back on but if i rev the engine the oil light went off. But came back on when it went back to idle. Is this the oil pump or the oil pump screen? Any help would be apperciated.

Thank you