2003 Intrepid Engine Light question

at first the engine light could be shut off by retightening the gas cap. Now when it comes on, it 'dings' and the car shuts down (while driving) I just turn the key off, throw it in neutral and restart but when I put it back into drive it runs like it has a gas tank full of water, so I put it back in neutral, shut if off and restart again then it runs like normal. I did the key on-off thing to get diagnostic numbers but mine don't show up in engine-light-flashes? The numbers show up in the odometer? anyway the numbers P0344/P0340 showed up and I found "Camshaft Position Sensor A - Bank 1 CKT Intermittent" and "Camshaft Position Sensor A - Bank 1 Circuit Malfunction" So is the camshaft on it's way out or is it just a sensor or worse? Thanks for any info.
Lise