Rent a cooling system pressure tester and see if it will help you determine where a leak might be. If there are no external leaks, that just about leaves a head gasket as suspect.

Take a look at all your plugs and see how they appear. A compression test might also prove useful.

 

I don't have a puff of smoke on anything on start up. And the weird thing is is that it will be fine driving around and stopping and everything but once I turn it off for a few minutes and go to start it up again then there's all sorts of air in the system and the only bleeder that has air is the lower one near the thermostat which I don't get I'm in the process of tearing everything down right now and I'm most likely going to get all new hoses since they are the original GM hoses so they're about due anyways. I never had this problem till about 2 weeks ago when I left the car sitting from saturday morning till monday morning and the last thing I did to the car lately besides an oil change was the intake manifold leak but that was over 2 months ago.

 

I had the same problem in my car, light came on when the sytem was full. I unhooked the low coolant sensor, problem solved.

 

The low coolant light is the least of my worries right now. The light coming on was the 1st sign of problems with the cooling system.