camshaft position sensor

I have an 04' Armada and I need to change the camshaft position sensors (both need to be replaced) but I am having a hard time locating them. If anyone could direct me that would be aweosme. Also am I causing any damage to the engine by driving it? I know that there is a loss of power and an increase in fuel consumption, should I change the spark plugs once the sensors have been changed?

thanks for any help:)