should I replace water pump 20054runner

[runningred]

I hope someone can help me out! 20054runner with 200k miles . V 6 Blows cold air at an idle
Changed thermostat with no better results. Flushed heater core with squirt bottle and air
That changed but very little!
Bottom radiator hose cold. Top radiator hose hot. Could be something other than water pump? Can I do water pump my self? Is there videos?

 

[Mike07SE]

Could be a blend door issue.
Does the truck actually warm up like it's supposed to?