What is the name of that circled tank? Thanks in advance!

 

That I believe is called a "helmholtz resonator" (aka resonance chamber) but not sure what Ford calls it.

It and the other elongated tube on your intake basically cut down on intake noise. I could be wrong but I'm pretty sure that's what it is.
Most people end up removing them and plugging the holes.

Here's a pretty good write up on what they do:

http://www.ehow.com/info_12156112_ai...onator-do.html

My 2003 2.3L XL does not have those on the intake tube and it's kinda throaty when accelerating hard. I think Ford got rid of these
intake resonators after 2003 on the 2.3L's.


On a similar note you can also weld a helmholtz resonator on the exhaust system (perpendicular to it) to move the drone frequency up or down the RPM band as well
as attenuate it some.