For the past few months, my 95 Maxima (193,000) has been sputtering after driving it for a while (most likely after it reaches normal operating temperature). Recently it's gotten worse to where when accerlerating from a stop, you could feel the misfire or even hear a small backfire. Read the codes and only thing that popped up was the Knock Sensor. I have always run Regular 87 gas in this car and it's never been a problem except for the Knock Sensor.
I replaced the plugs and it seems better but still will misfire or even backfire, almost like it's loading up a cylindar. Today I replaced the PCV valve and the fuel filter (was time for both) and hoping against hope that would help too. I haven't driven it far enough to know that but it did still sputter and felt like it was bogged down with gas.
So how do you diagnose this if no codes are being thrown except knock sensor? I have put in fuel injection cleaner and that does seem to help when its in the tank or maybe thats my imagination. It's time for a fillup so I could put premium in it to see what that results in too.