My Sentra started having some problems a couple of days ago. I was pretty close to empty when it happened. The exhaust sputters irregularly, and when I floor it, I get no response. I have come close to stalling out a couple of times too. I have changed the distributor cap, spark plugs and wires, and fuel filter. My next step will be the O2 sensor. I was wondering if anyone might know what the real cause of this problem is, and if they have any advice on what to do. Thank you.