My first thought was that you had a leaking LIM gasket. But, you just had that replaced, so thats not it.

Second thought (and pretty common actually) the sensor.

 

Ok I had the dexcool flushed and the low coolant light still comes on could I unplug it for now? I reallly want to take it off and try to clean or replacee it but don't know how to get it off... does it screw off?

 

2000 Monte- 3.8. I just replaced my Lower & Upper intake gasket TODAY! It wasn't that bad. It was may hours of getting to the core of the engine...but I tell you what- the gaskets were pretty bad. I mean, sludge was EVERYWHERE. the buildup of years of dexcool was also evident. But, the job is done...I pressure washed the lower manifold and its new again. I completely flushed the coolant system and added Prestone Dexcool. I am sorry to say sir, you have a long day of work ahead of you. You are trying a simple fix for a deep rooted problem...good luck.

 

its probably just the sensor on the left side of the radiator i unplugged mine and the light went off til i get it replaced

 

Well i put a new one on two days ago.It did not last 100 miles and is back on.It will come on and then off at intermittent times and now acts as if it is on to stay.
The one i am replacing it with is the lifetime warranty sensor from
O'Rilley Auto Parts.
Is it time to ask for my money back and go to GM?
Is there something I am missing? How about some kind of professional installation procedure.