Low coolant light stays lit when coolant isn't low. Intake manifold gasket was just changed and coolant light lit up on startup. Coolant level is topped up and no leaks.

Coolant leaks,When the intake manifold gasket cracks or blows out, coolant will leak out of the intake manifold. You may see puddles underneath your car or notice smoke or steam coming off of the engine and exhaust from the coolant dripping onto it and then burning.Overheating, If the intake manifold gasket fails and allows coolant to leak out into the engine, your car will begin to overheat. If your car frequently runs low on coolant or begins to overheat, check the intake manifold gasket.Running poorly, When the intake manifold gasket falters, it affects the way the motor handles its emission gases. The change in pressure can affect the vacuum in the intake as well as how smoothly your car runs. Mainly, it will idle roughly and may hesitate, cough or sputter.

oil too low!!!!!!!!!!!!!!!!!!!!!!!!!!! have some change your oil & filter immediately !!! drain radiator & coolant reservoir , refill w/ fresh 50/50 coolant , white smoke is not exactly a good thing ! it could mean coolant is mixing w/ oil , because of a possible leak from a bad gasket either from intake manifold or head gasket !!! water pump would not cause this ! I would bet on a gasket leak given the age of the car . 2000 ! 13 years old, how was it maintained, intake gaskets are cheaply made, head gaskets are made well ! so, my bet, goes to the intake manifold gasket !!!!!!good luck kristle !

I would perform a coolant pressure test because these engines are known for leaking intake manifold gaskets.Check and see if your oil is starting to turn a creamy tan color.

with milky oil stop driving it sounds like intake manifold gasket will need replaced and oil and filter change continued driving like this will destroy lower end of the engine

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Check the coolant reservoir and the radiator for proper coolant level. If low you probably have a leaking intake gasket or possibly a head gasket leak. The intake leak will be visible on either end of the intake manifold, located at the very top portion of the engine. The head gasket usually shows up at the rear head, nearest the belt. You could have a water pump leaking and this would show coolant on the ground under the right front of the engine, more so when the engine is running. They are very common for all 3 problems.

Uh oh...You may have the Ventures infamous head gasket/intake manifold gasket failure. First check your coolant level,not just in the bottle but in the radiator itself. Change your radiator cap. Make sure the rubber hose leading from the overflow tank to the radiator neck is not kinked and allows water to flow in both directions, not just into the bottle under pressure. Dex-Cool is very sensitive to exposure to air and tends to clog the system if air is allowed in. If you are low in coolant, flush out the system and from my experience I would change over to good old green coolant and change it every 30-40K. If your coolant level isn't low you may have a stuck thermostat (located sideways under the throttle body) or head gasket problem. A cheap check for a head gasket leak thats still small is to open up the radiator on the engine while its cold and start it up. A bad head gasket will send exhaust into the water jacket which will force the water to bubble up the radiator neck before the engine is even warm. A bad intake manifold will burn antifreeze out your exhaust and drain your radiator without any sign of a leak.

THERE IS A PROBLEM WITH THESE SENSORS, IF THE COOLANT ISN'T LOW REPLACE THE SENSOR.

The valve cover gaskets will leak and cause the exhaust manifolds to smoke. You will notice it when you park car or at a stop light.

YOU NEED TO REPLACE THE UPPER INTAKE MANIFOLD. ALSO, YOU WILL NEED TO REPLACE THE LOWER INTAKE MANIFOLD GASKETS. THIS IS A MANUFACTURING FLAW. THE PLASTIC INTAKE CRACKS CAUSING AN INTERNAL COOLANT LEAK. YOU CAN RESEARCH THIS ON LINE.

You answered your own question in your question. The clue is the add coolant light. My guess is that it is low on coolant, as to why it is low there is probably a leak somewhere. GM had problems with the 3.8 upper intake plenums on the series 2 engines, and the 3.1 and 3.4 engines had problems with the lower intake manifold gaskets. If you still have the pink antifreeze in it you should take it back to the dealer as GM just lost a class action lawsuit about their Dexcool eating up intake gaskets. It is possible that if that is your problem GM will pay at least a portion of the repair costs. Hope this helps.