I had an issue with my wife's 99 LS where the fans wouldn't kick on at the temp. it would go one notch above the middle line and then fans would eventually come on. I downloaded the bin file from the PCm to see if I could change the temp where it came on and it said it was "corrupt". I ended up finding another L36 Bin for a 99 Regal LS and it's been fine ever since.
Not saying this is your fix but it might be.