spuratically my car will excellerate in RPM drastically and then there is a slight drag in power. It is not isolated in one or two gears I have noticed this in all gears. Originally I felt it was the catalytic convertor so I switched to higher octance cleaner gas and did not have any issues of reoccurance for 2-3 months. It typically has more issues when it is colder or if I do not let the car warm up. DOes this sound like o2 sensor , Catalytic convertor or a tranny problem. NO issues shifting it is a manual 6 spd not the 5 spd riddled with issues.