Hello all my car has around 209,000 miles on her, and is still running fairly well. I was able to get around 400 miles to a tank of gas, but as of late not so well. The current tank lasted around 310-315, and depends on what type of gas I run in it. I have recently done a tune up on it, plugs wire and pcv valve. But nothing I do seems to help much. I was wondering if replacing my 02 sensor would help? I heard that the top 02 sensor regulates air/fuel consumption? Or something like that. I have a cold air intake, and I am running an MP3 ecu. If anyone has any suggestions it would be greatly appreciated. Thanks for your help. Chris