What are you using to check your engine's temperature. If you're using the gage on the dash, it's possible that it could be off. They aren't always totally accurate. I would check the temperature of the engine right at the engine itself; or look at the live data to see what the computer is seeing. Also, have you maintained your antifreeze? DEXCOOL vehicles are more prone to the coolant getting thick, and possibly plugging passages. Even though it hasn't been a huge problem for the 3.8L's, it may be something to check into. If you do, remember to have the system flushed completely, and not just changed. Also, at what temperature do the fans turn on?