I have a cylinder #1 missfire I cant get rid of. Engine runs smooth most of the time and the only way I can feel it is to power brake it at about 1/4 throttle. Have replaced sparkplugs coil injector and intake manifold gasket. What else could be the problem. It is a 2004 maxima and that is the only way I can get it to miss and not every time.

Did you use OEM coils? NGK plugs? It could be a broken wire in the harness or bad ECU, but both of those are relatively unusual problems with Maximas.

Cam shaft sensor?

Failing o2 sensor? Check Engine Light on? I was having random misfires. Car would pull fine some days and miss on others. Slowly begun getting worse. Eventually the car threw check engine codes for o2 sensor bank 1 and random misfire. Changed the o2 sensor and performed the Air/Fuel Ratior relearning procedure and car has been fine since.

I changed crank sensor and cam sensor on rear bank. Does front bank have cam sensor too?. Have not changed O2 sensor. Which one should I change or all? How many does it have? I used OEM coil and sparkplugs

Yes. Front one is actually piece of cake to replace using 10mm tool within 10 minutes. The only thing you need to make sure is to must get an OEM sensor. Amazon sometime throw a decent price for OEM sensor.

Go with camshaft sensor first which is easy to replace but will cost under $100 for sensor. There are 4 O2 sensors and if you have a good scanner then it will be easy to find out if one of the sensor is lazy or not working.