Nissan Repair: PO325, air fuel mixture, knock sensor

Question
I have PO325 on my 1999 Nissan Quest 3.3. The engine runs fine with the exception of a slight shake in park and less noticeable in drive.There is some fluctuation in idle but not much. MPG is 14.5 which I think could be better. I have been reading that the knock sensor is irrelevant to performance and is notorious for malfunctioning in Nissans (which means PO325 means nothing?). Should I go through the expense of changing the knock sensor in order to get a better idle and mpg? I read that the knock sensor controls timing and I'm thinking that might solve my problem.  

Answer
A knock sensor tells the engine computer when one or more of your engine's cylinders are "knocking", that is, exploding the air/fuel mixture in a way that delivers less power and can be damaging to the engine if prolonged. The computer uses this information to tune the engine so that it doesn't knock. If your knock sensor wasn't operating properly, so that it was always indicating a knock, the engine computer's response may have been to change the ignition timing on your engine. The knock sensor generally threads into the engine block. This P0325 code may show up intermittently or the Service Engine light may be lit constantly.
Yes, replace the knock sensor.