P0133

Hey, I have a 2000 sc2, 1.9 with a code p0133 stored. The car idles fine and runs good til it gets operating temp. At half throttle it feels like the car starts to buck and jerk. Tested fuel pressure at idle and when the car messes up and they were at 45 psi each time. Replace fuel filter and spark plugs, plus wires still no help. Replace o2 sensor with non-lazy o2 from dealer and as replace rear o2 sensor. Still no help. Now get this, if I unplug front o2 sensor car runs great but turn the check engine light for no voltage from o2 sensor. Please if anyone has an idea it would be great.