You guys have done a great job of laying stuff out for the OP. Basically, if the fan is working right, thermostat is opening properly, coolant is full, Rad cap pressure tests fine and the Rad and coolers are not gunked up then the truck will not over heat. (The default fail position for the auto shutter system is open, so even if they failed that should not be the problem but easy enough to check as they go through a test cycle every time you start the truck.)
The Op insists the fan is fine, thermostat is fine, coolant is great and the Rad and coolers are clear. I cannot wait to hear what is causing this truck to over heat because it must be possessed if it is overheating and all those items are fine.