a choke heater indicator light.  You are probably 
having trouble with the solenoid that directs current to the choke 
heater that "turns the choke off".  I was having trouble with the one 
on my '84, and the car was running extremely rich as a result.  The 
solenoid (at least on my car) is dark green or black, about a cubic 
inch in size, and located under the air intake tube on the passenger 
side of the engine compartment.  Replacements are available from the 
local Chevy dealer for about $7.