Individual codes P0341, P0405

P0341 on Saturns is usually caused by an engine misfire (even though the code states that it is for the camshaft sensor). The first thing you need to do is check your spark plugs, wires, etc. If you haven't replaced them recently then you should just do it. It could also be caused by the spark plugs as well.
P0405 is for the EGR system. This particular code is probably caused by the EGR valve itself or a wiring problem. Be sure to check the connections to the valve and the wiring harness.

Just to add this one the code P0341 has nothing to do with the engine missfiring. That code sets when the cam signal received at the pcm is incorrect or has too many pluses per cankshaft revoultion when the engine has been cranking for 5-10 seconds or when the engine is running. Also the engine doesnt have a cam sensor. What usually happens on those cars is the spark plugs and spark plug wire ends where they meet the plugs build up black carbon. That black carbon throws off the so called cam signal and sets that code P0341. Your on the right track though usually replacing the plugs and wires fixes that code. Also make sure you put in the stock copper ngk plugs dont put a platnuim plug in that engine. They will carbon fowl in those engines.

I posted the trouble tree for your code P0405 let us know what you find.