I get a misfire in cylinder #6 change coil , work for about a month then started up again , any suggestions would be greatly appreciated

 

Where'd you get the coil?

 

got it at autozone

 

But I don't think it's the coil cause nissan replaced the number 1 cylinder coil and I swapped it with the autozone one and it still give me a misfire on cylinder 6.

 

OK. You mean code P0306. It could be a clogged or failing injector on cylinder #6 as well; or compromised wiring that connects to coil #6, or injector #6. Check the condition of those harnesses and the wiring leading to those harnesses. Also, check for vacuum leaks in the intake system: Throttle body, Intake plenum(Although least likely to throw that code, but possible).