2000 Nissan Maxima P1320, p0420

Hi, I have a 2000 Maxima, recently i have the code p1320 for 4times and p0420 for 2 times, couple of times after I started the car and the engine was shaking like missfired and smoothed out after restarted. Also sometimes rough to start but always can start the engine when retried(I don’t know if this is related with key cylinder).I just changed 6 ignition coils(oreilly coil). The code p1320 came right back. Autozone told me to change the camshaft position sensor, I don’t want to waste my money, Can you guys tell me what to do. thank you

There’s a Technical Service Bulletin from Nissan for this problem. http://autorepair.about.com/library/a/1i/bl039i.htm

Tester