O2 Sensor Problem???

Hi I have a a 2001 5 spd standard SL Series Saturn and I recently have a problem:

My car misfires a lot which makes the car jump a little or sputter a little a low RPM's and it has a really hard time going up hills and also its really hard to shift as it seems like the engine doesn't catch on...

Now for the start of my Diagnosis

I had 3 recent problems
P0300 Ramdom multiple cylinder misfire
P0341 camshaft Position circuit High Input
P0440 Evap. Emmission control System Malfunction

Now 6 months ago I had a different problem but I never got to fix it
P0130 O2 Sensor Malfunction

Now I repaired it 6 months ago by replacing the gasket because I had a leaking manifold gasket and it fixed the "fix engine soon" O2 sensor problem for 3 months and I didn't replace it

Now I'm feeling the brunt of it with my problem above

Now the question I'm having is:
is The broken 02 sensor causing the problems?so I should I replace it? or is it more than that and it is a totally different problem to the misfiring that I am getting?

I would say that most of your problem is the Cam Position Sensor code followed by the p0300 code. I would replace the cam position sensor and then give it a new set of plugs and wires. Don't get fancy with the plugs. Just use some standard copper core AC Delco plugs or Autolites. Some platinum plugs can cause problems with these ignition systems. Make sure you gap them properly. There's no such thing as a pre-gapped spark plug.