91 explorer over heats after going uphill

My 91 explorer seems to get very hot after a 45min uphill climb to my house. When I get to my driveway and shut off the car the resevor is boiling away. And the temp guage is almost at max. I just changed the thermastate thinking that was the problem it didnt help. Any other ideas?
Also the water pump was replaced about a year ago has it gone bad? Is it the mixture of antifreez and water ? Thanks

Could be a badly clogged radiator. Maybe a water pump, but, how old are your coolant hoses? I have heard stories of the bottom ones causing problems due to collapsing when under stress, when the metal coil inside of them rusts away. The spring coil keeps the hose from collapsing when running, otherwise your engine will overheat. Also heard of the rusted parts going into the engine and causing problems. Maybe try replacing hoses and flushing well.

My 91 explorer seems to get very hot after a 45min uphill climb to my house. When I get to my driveway and shut off the car the resevor is boiling away. And the temp guage is almost at max. I just changed the thermastate thinking that was the problem it didnt help. Any other ideas?
Also the water pump was replaced about a year ago has it gone bad? Is it the mixture of antifreez and water ? Thanks

First thing to check... thermostat unit, I am certain needs replacement. Mine.... 4x4 , 1997, had same symptom replaced thermostat and kept on cruising....