Previous leaking/blow intake - question about upstream o2
Back at the first of the year, My '00 SSEi blow the intake gasket. When I bought it in July '07, you could see that it was seeping coolant around the injectors and near the heads. December 30, '07, and not even 3,000 miles later, I decided to tear it down and replaced the gaskets. A couple days later, a little bit of money, and one torn injector o-ring causing a misfire, and the car was road worthy again. I had to replace the vacuum boost harness because underneath the supercharger snout, due to age and heat, the vacuum hoose cracked into pieces.
I just wonder if from the leaking intake, and possibly blowing coolant through the exhaust, if my upstream o2 sensor is coated and not reading accurately anymore. I just don't feel I'm getting the greatest mileage out of the car. It is winter time, and winter blend gas, so I'm not sure if that is effecting it. The car has around 138k miles on it, and to my knowledge, has the original o2 sensors.
Any ideas would be appreciated. Thanks