That sounds like the same things I had going on with mine. Plugs etc.. will help clean up your miss fire's and possibly a few other codes. Iycleaned up my cat. converter and miss fire code's. Its an easy job that takes about 20 mins. Now I need to do my EGR valve. On the other post there's a link to nissan help website. Not mocking this site but they have alot of How-to step by step stuff. Good Luck.