96 Explorer, Check engine light on for 3rd time, help!

OK, originally I took my 96 Exlporer XLT with 108,000 miles to the local mechanic because the check engine light came on. He said the code was for a poorly performing Catalytic Converter and turned the light off. Then it came on again only a few hundred miles later so I took it back, same diagnosis but this time he said 96 Explorers had a software glitch that made the light come on, so he turned it off again. Now it is on for the third time. Each time the motor runs perfect, so is there a glitch in the software or should I take it to another mechanic?

Whenever my light has come on my engine was running fine but it turned out to be an early warning about my o2 sensors

Did you replace all of them? I think there are 4.

Yes there are 4 and I did replace them and ever since then my light has stayed off. I am not saying this is exactly what is happening to yours but just that was my experience.