Ford likes to use a LARGE hose on their engines, and it is in a difficult spot, right behind the TB.
Like I said, it's a large hose, so you will need different style caps. These will not be in any assortment of vac caps I've found, but I HAVE found them! They are sold under the label of "Heater Hose By-Pass Caps" and can be found for about $6 at most parts houses packages as an assortment of sizes.
I buy mine in bulk from Sherco-Auto.com. Their catalog can be found here:
. Just hit control + f and search for "bypass" and you'll see them pretty quick. Their numbers are HB 1 (3/4") and HB 5 (5/8"). You should have both on hand unless you know for sure which they used in this case.
I don't!
The hose can be difficult to reach, so prepare yourself for some tight quarters! Just reach in and turn the hose, pulling at the same time to release its grip. Be patient, as sometimes it takes a bit of finnagling!
Once you get that line capped, watch for some great power gains!