How long have you had this problem? Do you always use premium gasoline? Do you do a lot of city driving with stop and go traffic? Have you taken the car on a long trip (over 200 miles) recently? I know this will sound mundane, but you'll want to weed out the minor variables before you start weighing in on more complex / expensive epairs. Heres what youve done so far:

• Transmission and oil change
• MAF cleaning
• Chevron Fuel Additive
• Fuel filter

The O2 Engine Codes you received could possible mean:

• Faulty o2 sensor Exhaust leak near the rear sensor
• Plugged catalyst
• Short to voltage on O2 signal circuit
• High resistance or open on O2 signal circuit
• Engine running very rich or lean
• Engine misfire condition
• Fuel pressure very high or low - fuel pump or pressure regulator

Get the engine thouroghly cleaned. Pour a bottle of CATACLEAN into your fuel tank and go for a nice long highway drive. These cars have high performance engines and require long periods of peak operating temperatures. Short drives, stop and go traffic and poor quality or lower grade fuel will affect its performance. Just my 2 sense. Good Luck