.2001 Buick Century.. Son said car was overheating.

Got a stumper here...2001 Buick Century..
Son said car was overheating. His Dad and I began diagnostics. The heat is
working in the vehicle. Took out and checked water pump, pump is working
fine. Back flushed the radiator amd system..no clogs, no air. Let car run for
over an hour in the driveway, fan kicks in at 240 degrees and not at 225. So
we checked the TSU. It is working fine as well. When we took it for a
drive...the    dash showed over-heating, but via gauge and "Torque" program,
never went above 250. It does not drop in temp at all no matter how much air
flow from driving. Even on freeway it didn't drop a degree. Sitting at idle still
doesn't go past 250 degrees. Water flow through system has all been tested
and no clogs. After running an hour in driveway, then a 45min drive, checked
hoses and they are only warm. they should be way hotter. What are we
missing? Also, no smoke from car, no other signs of overheating other then
the gauges and torque diagnostic program showing the temp to be 240-250
degrees.