2001 Volkswagen Jetta

Check engine light was on, code came up as P0341 to replace cam shaft sensor. Car seemed to lack power. Replaced cam shaft sensor, timing belt, spark plugs and oil. All tiiming marks were aligned. When code is reset by auto parts store and then driving away code stays off. As soon as you shut car off and restart code reappears. Car still lack power as well as check engine light is on. What could be the problem and how do I fix this problem.