thats a coolant hose that sends coolant through the bac and then into the throttle body

 

i think youd have to pull the upper intake manifold to replace the hose

id also make sure to replace the pulsation dampener or delete it when you have the manifold off. also would be a good time to clean fuel injectors and replace vacuum hoses if they're original.

 

it's hard metal deposits on the aluminum. meaning you need to flush the cooling system more often. you can remove the hose and clean off the cocaine and snip the hose back half an inch.