'96 Deville cooling system problems

In the last two years, I've replaced the radiator, the heater core twice, the water pump, the AC compressor, the holding tank and all the hoses.
When I'm on the road in approx. 85 - 93 heat I run the AC all the time.
Both fans are running.
I have 90,000 mi on this car but it still runs good, gets 24.4 mpg highway, 21.4 city. I use shell 10W-30 oil.
I understand this year with the Northstar engine is supposed to run hot, aroung 221 degrees but sitting at idle it runs approx. 251 degrees.
When I get back on the road it will drop to 239 or there abouts.
Anybody got any ideas? Does this car have a thermostat in the colling system someplace?

Appreciate any help,

budz2

Those temps are a bit high. If that stat is original it's due for replacement. I'd go with an OEM stat from dealer parts or a Stant brand from any decent parts store.

251 is pretty warm for a Northstar! Does the coolant look ok, and doe it consume any?
The thermostat is located on the waterpump housing. You will see where the lower radiator hose goes into the housing, and under the black stamped steel housing is the thermostat.