Ford e-350 overheating problem

I have a 1998 ford e-350 5.4 triton. It is overheating, mainly when going up hills. It does not overheat when driving on staight aways or down hill. It also does not overheat when sitting idle. I have removed the thermostat and it still overheats when going up hills. I see no leaks anywhwere. With the thermostat out I can feel the water flowing through the top hose and the bottom hose gets hot. I am rulling out the Rad. Can you help?

I read in another thread how to check the clutch motor. I did so and mine seems stiff. Its hard to get at with the shroud in the way but I can barely get it to make one complete rotation in either direction. I am really stumped here.

I have an 89 E250 that once had a bad fan clutch and overheated going uphill. New clutch, no problems.

Check the air passages for bugs some people use a bug screen. Use a garden hose and flush both the condenser in front of the radiator and the radiator.
Look over the fan clutch for leaking fluid and if it will rotate check for broken blades. Check the belt is tight enough. Make sure the fan shroud is installed properly. Check the hoses have springs and don't collapse on you.