Well it could be low oil pressure. That light is designed to go on at about 5 PSI or less. Then, when you accelerate, the oil pump starts a greater flow and your oil pressure goes up, and the light goes off.
First thing I'd do is check the oil pressure with a REAL GAUGE that you screw into the oil sender fitting. That gives you real data (a Chrysler type scanner might also be able to read this).
If the oil pressure is genuinely below 5 PSI at idle, you'll have to drop the oil pan and investigate for a clogged oil screen, loose or dented oil pickup tube, a worn out oil pump, or worn engine bearings.