Do you have access to a ScanGauge, or similar type gauge to hook up to your OBDII connection to get an accurate temperature of the coolant?
Do you have one of those inexpensive laser temperature guns to check around your coolant flow path to see where the temperature is being generated. In other words what is the temp of the coolant in to the radiator and the temp out of the radiator.
I believe that your transmission fluid also runs through your engine radiator. Is there any chance that your transmission is running hot, for whatever reason, and this is affecting the engine coolant temp?