intake manifold sensor

There is a sensor on my intake manifold that is leaking gas. Its on the passenger side below the pcv hose. Its constantly damp. Does the sensor screw out? Or do i need to drive it out somehow? Also my motor knocks. Its not a harsh sound but it sounds deeper and heavier then a lifter. Could it be a wrist pin? How hard would it be to fix?

What year...what engine

If you got a sensor on yer intake leaking gas-you prolly got a leaky injector.
Like WhiteCavaliac said, what year?, what motor?

Lifters can make a hella noise when they wear out and/or collapse/stick.
My 2.0L made god-awful clanking noise when a couple compensators got stuck and wiped out the cam and rocker arms.
Wrist pin involves piston removal-you can do that without removing the head-just the pan/crank shaft/mains, etc.