dustin' off the oldies here.... I have a feeling that something like this might be going on with my truck... got the cooling system flushed when I bought it about a year ago, and... actually I have the work order in front of me here so lets see what they did....
"Drain cooling system. Remove t-stat + upper rad hose. Flush cooling system in all directions multiple times. Flush cooling system with engine running by removing upper rad hose @ rad + running water into radiator. Replace t-stat + refill cooling system. Purge. Check for operation. Check rad cap= not holding pressure= replace"
Despite this... after a good afternoons off-roading or a medium length freeway blast, my engine often starts to smell quite warm even though the temperature gauge shows normal temperature.
If I have the HVAC off it starts sending warm air into the cabin. And if I have the AC running it starts to fad significantly.... I have checked the AC system and it has plenty of coolant, so I don't really know whats going on... I do hear the fan going when I first start it up in the morning, but I think I will have to start by checking that. Although... is the fan controlled by the t-stat or does it have it own independent control?

 

my 2005 Jimmy was overheating so I changed thermostat flush and new antifreeze still overheating rad looked clean could not figure out what was wrong , I then happened to look between rad and the condensor, wouldn't you know it plugged solid. Made myself a long air blowgun with a 90* bend and was able to get between the two with very low pressure and running water. Took a while. Went for a ride and temp went right down.
I forget what temp. it went down to but it was exactly what the dealer said.
Hope this helps

 

just looked in the manual for my 98 and it says that the thermostat starts to open at 195. and think about this, it is an analog gauge on your dash there. if its runnin at 210 on the gauge its probably not the thermostat. i would check the radiator and the a/c condenser. if its all plugged up with junk then its not going to cool too well.

 

Pettyfog, the graph you show looks kinda strange, hp and torque curves ALWAYS cross at 5252 rpm, just saying.

 

When they are on the same axis, that is true as the relationship between power & torque is a fairly simple equation. In the case of the subject graph, torque and power are displayed on two different axes and the torque axis is scaled 2:1 compared with power which is why it appears as if they cross at ~2600RPM.