I had a check engine for a long time, and overheating when pulling a heavy trailer up long steep hills. It was dismissed by dealers everywhere until I put a rebuild engine and transmission in and the light stayed on. It turned out not to be the O2 sensor, it was a clogged catylitic converter. (That may have been the problem on those long hills, or alternatively the exhaust gas temp may have gotton so hot on these grades that it melted the element in the converter. Anyway, it sure runs better with the converter element knocked out. The check engine light comes on sometimes and goes out sometimes, but mileage is increased dramatically, like maybe the acetone helped melt out the converter?
good. I never like that converter anyways.