Problem code p1320 came up on my diagnostic

Here's a link to your code.

Is misfire #5,bad plug,wire,still could be module.

Here is a link to a Nissan forum that discusses your problem..In the 2nd post there is a link to the service manual for trouble shooting this issue. It seems that it is more common than not.

http://x.nissanhelp.com/forums/maxima/9813-2000-nissan-maxima-p1320-code.html

P0420 =CATALYST MALFUCTION
P1320=NOT SURE ,I THINK MISFIRE

I found a thread on Maxima.org relating to the P1320 error code. Specifically, 2000-2001 Maxima's have had this problem. It seams as though everybody agrees that the error is caused by the ignition coils. We've never had ours changed, so I'm doing that. Nissan was going to charge me approx $600 (plus tax) for parts and another $180 for labor. The job take a whole 30 minutes to replace the 6 of them, and you can get the 6 ignition coils at O'reilly's for $325. I changed three last night and the car seems to be doing better. I'll replace the other 3 tonight and see what happens.

Also, when testing the car, the car seems to "shake". I'm not sure if this is related to the P1320, but if we turn off the AC the "shaking" stops.

Hope helps (remember rated this).

2000 maxima are famous for having bad coils - those cost about $350 if you dealer isn't trying to rip you off (otherwise they will charge $600). I also read you can get an aftermarket coil at Autozone.

P1320 is the Ignition Signal Primary. There is a technical bulletin for this code for this vehicle. To remedy this issue, you will need to replace all 6 ignition coils. I suggest that you purchase them from a Nissan dealer to make sure you get the right ones.

Primary ignition fault. Reasons: Bad distributor cap (most likely) or ignition control module/ignition coil.
Hope that helps
Good Luck