Well I would definitly re-check the spark plug gap. Also for some reason Nissans are very finicky about the plugs you use. Make sure you are using NGK or Denso plugs. I have seen problems develop from using Delco or champion plugs. But you may want to get the ECM checked for any codes, usually Auto-zone will do this for free. You may have some other problems. Is the car missing pretty steadily, even at idle? Or is it idling normally?
It may be that you got a faulty coil. Can you isolate the miss to an individual cylinder? If you can, then try moving the coil from that cylinder and see if the miss moves. I have seen brand new coils bad, especially aftermarket ones. Like I said though, I would try and recheck the gap too.
Sorry I guess I was confused and thought you had replaced all the coils, not just one. Well that year maxima was know for coil problems, usually you get a "ignition Primary" code. In which case you usually have to replace ALL the coils. The ignition primary code basiclly means that it is detecting a miss on more than one cylinder. So at this point I would recommend replacing all the coils and it will fix your problem. I have probably replaced the coils on at least 50 maximas for this problem. Hopefully this helps.
Well the ignition primary code is saying that there is a misfire in multiple coil, not nesecarily all of them. The first thing you need to do is determine which coils are misfiring. Basiclly you need to do a power balance test. Basiclly what you are going to do is while the vehicle is running you need to disconnect individual coils one at a time. Some when you disconnect them will cause the engine to run worse. Those coils are the good ones. Some you are going to disconnect and they wont really change how rough the engine is running, those are the suspected bad coils. Now in order to ensure it is a bad coil, try moving that coil to a cylinder you think is a good cylinder. If the miss moves to the good cylinder, now you know you have a bad coil. And presto, a little work and you can identify the bad coils. If the engine still runs and is semi-drivable then you probably only have 2, maybe 3 coils that are bad. Now if you move swap some coils and the problem doesn't move then you know now that the problem isn't a coil, it is possibly a spark plug, or possibly and injector. Hopefully this will help you get a little cheaper alternative. If this helped then please accept, and tips are always appreciated.