Check the hose that goes from just under the radiator cap to the coolant reservoir. It is a closed system and when that hose gets old it can collapse closed causing the engine to overheat. I replaced everything from water pump, temp sensor (swapped with an analog gauge which came with a sensor), rad x2, fan clutch, then fan (tried electric as well), unhooked and bypassed heater core (to make sure heater core wasn't possibly clogged), thermostat, and thoroughly went through the engine. That is when I barely noticed the hose pinched, I replaced it 2 years ago then drove it to Texas and back to Montana, My 30 yr ol’ 22RE D.D. and trail rig hasn't overheated since. Old post but so many still on the roads and trails, thought I'd add another possible solution. Long live the Yota pickups and T4