I am looking for some help trying to diagnose a small pulsing noise after I have driven the car for a little bit and I am at an idle. I feel like it started after I ran the fuel down pretty low a couple weeks ago. I have used premium fuel since I bought my S60 a couple years ago. I am guessing running the fuel low, I may have sucked some dirt or something through the fuel filter. The accelerator pedal seems a little bit less responsive at the top. Any opinions?