Now that sounds like what the problem might be. I have ordered that sensor and am waiting on delivery. My driving temperature is below 80 c. When I come to a stop it slowly moves up to 80 c. If it's hot out and I sit there, it will eventually get to 90 c and hold. If I take off and drive again, it will drop back down to 80 or lower depending on drive distance. I hope that is the problem and the sensor makes a difference. I certainly noticed a difference (improvement) when I replaced the O2 sensor. Thanks!