I unplugged this(doing the valve covers) and I can't seem to find the hose the was connected. What does it connect to? What is it? Do I need it? What does it do?

 

There is a temperature controlled vacuum valve somewhere - It uses that servo to move a flap to draw air from a duct that goes down to the exhaust pipe to get warmed air to the intake when it is cold outside.

The valve is also connected to manifold vacuum.

The warm air duct from the exhaust should come up to the underside of the air intake duct, about where that servo is.

Looks like someone in the past had an understanding of what it is and does ( or should do if hooked up and everything else still works) going by the extension on the intake schnorkel.

I think it's default is flap opens to open end intake and vacuum pull internal flap down to breathe in exhaust warmed air, so it stops functioning as intended may just be bit piggy when engine temp is below op temp.