The hose that went bad for me was a little 3" 'L' shaped hose directly off the back of the intake. You wont hardly be able to see it the way Ford tucked the motor in under the fire wall. With it running reach back there and feel around. If theres a leak you'll be able to feel it and hear the tone change when you put your finger over it.
I'm telling you this because I've heard other people have the same hose go bad.
The good news is this hose only cost about $8 at Ford.
Good luck.
John