2002 chevy trailblazer stall and oil light

When I stop at red light oil pressure gauge drops to zero and then back up and engine tries to stall. Then i take off and its fine, it only happens driving in town,not on interstate. Any help?

Answer: The light is coming on because it is nearing a stall. The stalling is the main problem.

Check fuel pressure, carbon in the throttle, scan the computer for codes.