[fireboss]

I have replaced the cap on mine but I still spill fuel out of the tank at every auto cross. The neck where the cap screws in is out of round just enough to piss me off. No matter how tight the cap I still get a leak. I only run 2 gallons of gas in the tank when I'm on course and it still leaks out the of the cap. This has never caused a problem with the way the engine runs.
I would check the air flow meter "spring tension' before I replace the O2 sensor. A week spring gives a false reading to the computer and you will have an over rich fuel mixture causing it to run really crappy on a cold mornig.