so many opinions when it comes to the lumina stall at red lights and eratic idle. I can tell you what I did, and it worked. first, syphon a pint of tranny fluid out of the tranny and add a pint of seafoam transtune. replace or clean the trottle position and idle air control sensors. drive the car normally for a couple days then get the tranny flushed. make sure to replace or clean the filter during this process. other things ppl have suggested is checking the cat converter, ignition module, spark plugs and wires. and the list goes on. do what I did first, then move on to checking the others. oh, and make sure you are doing the standards, such as oil changes and replacing the air filter and pcv valve. these are cheap things to do and will help your car stay running longer.
I see you live in columbia sc, Im north of you one hour "rock hill"...