Bad temperature gauge or sensor?

[Chamberpains]

Sounds like you caught a faulty sensor with the intake temp. So thats good. It may have been some of your problems.

I see you said you bought the high and low pressure switches on the Expansion valve. My t660 has both of those and the fan high pressure switch on the low pressure AC line close to the AC compressor. That is the 1 that actually turns the engine fan on and off according to what the AC demands. I dont know if your truck is wired this way but Did you replace that one too and check its wiring.