Ahmad Alsalem

I made a thread about my car bogging down before but didnt know the reason. I recently took my car back home to kuwait and we use 93 octane here, my car was tuned to 91 from RRE. I was gonna get it tuned after a week and drove it in the mean time (stupidly Going fast at times since i was waiting 5 months to get my baby!). Day before the tune the car started bogging down after i gave it a pull on 2nd. Took it to the shop and the guy told me a tune should fix that. When he took it out for a tune the car just started bogging like crazy so he couldn't tune. He explained that the issue was the O2 sensor was causing the car to run rich and was getting weaker. So he told me a simple change of the sensor and the tune would be the best solution. Also told me that was the reason my spark plugs were getting a little black. Does this make sense? I just want my Evo back to normal