there is a silver coated tube that is attached to a vacuum hose. it says NF1 on it and it runs to just inside of the manifold, now is that a check valve or what is it? because i noticed oil or greasy stuff on the outside of assuming its a check valve that it may be leaking, and that could also be whats causing my boost problem.

 

There is an aluminum check valve on the front side of the UIM (toward the front of the car). However, it's used in the purge control system. That valve shouldn't effect boost patterns/levels.