I have a 2003 Xterra and I have two codes showing from my check engine light, evap leak and knock sensor. I am replacing my knock sensor next week and since it is a pain what else should I change while I have the intake manifold off? I have over 120,000 on it. Also any ideas on to the best way to figure out where the evap leak is coming from?

FYI: the knock sensor will not set the MIL. It will set a code but the light will not come on. While you're in there, I would definitely recommend changing the spark plugs and wires since they're recommended at 120k.

Thanks for the advice. I have just received my parts and sparkplugs and wires.