Time... let the tube soak. make sure you use a small enough pipe cleaner to go through the constrictor otherwise you may push gunk into it and end up clogging it.
have compressed air so you can force air through.
when installing use appropriate anti-seize so future removal is easy that nut becomes difficult to remove with the heat and thermal cycles it sees.
The tube should be fairly clean given how much actually is able to flow back into the intake.
2001 ZX3 2.0L Zetec-
Hatch Nation #42
Going through Rebuild See "The TICK Build Thread" for details (http://www.focusfanatics.com/forum/showthread.php?t=289168&referrerid=62897)