06 Jetta, rough idle/vibration, shuts off. Code P0343

[mantsek]

I have a 2006 Jetta, that's been acting crazy.
When I start it, it revs up for a few seconds and starts to idle rough and vibrate/shake wildly, then the engine shuts off. The check engine light says Camshaft sensor (P0343). I have changed this in the past, and drove the car a about 100 miles, but the code came back. Then the mechanic replaced 2 bad ignition coils, and the car run fine again for a few miles and the problem returned. Now I'm wondering if the camshaft sensor I bought was defective, or if there is another problem. Someone suggested it is a short in the wiring harness- how do I check that?
Any help will be greatly appreciated. The car is out of warranty.