I got a NAPA fuel filter and just installed it in my camry and I was SHOCKED at how much better my engine sounded. It must have been really clogged bcos the rpms jumped from 750 to 1K. My engine had been sounding really rough when at idle so what I thought was a mysterious vacuum leak was actually my engine starving for fuel! The car responds much better, sounds better and drive better. I am still in disbelief. Thinking back on it I have owned my car for about 5 years now and have never changed it. Now I know better. So what's the interval of a fuel filter change? And I read somewhere that gas stations have a prefilter at the pump that catches a lot of stuff but if it isnt changed regularly (monthly) then its as good as not having one.