2005 Toyota Avensis P0430 code

On Avensis MIL light goes on. I reset it with OBD reader and light goes on again after 2-3 days and 60- 150 miles of driving. Usin OBD reader I chek at all oxygen sensors work properly. Voltage varied from 0-1 volts when start the engine. After catalytic converter heated up the voltages on the sensors after converters are stedy. I chek with multimeter at the preheating resistors are ok, resistanse apr 6 ohms. I enev took out the sensor before catalytic conerter and observ at the chells inside of the catalytic convertsers looks fine. No excaust leaks found on the exchaust pipe. So what I should chek next. By the wau the compter on this car was replaced 3 years ago by previous owner. I took the car for dealer and they told me at need to replace the catalytic converters and perhapsa 2 of the oxycen sensors before the catalytic converters. Cost of this repar wll be 1800 €, which money I really do not want to spend until I am sure at it really is the only solution. These are the images from the diagnostic I did.[img:e24689c36b]http://www.2carpros.com/forum/automotive_pictures/507594_long_therm_fuel_trim_1.jpg[/img:e24689c36b]
[img:e24689c36b]http://www.2carpros.com/forum/automotive_pictures/507594_oxygen_sensors_2.jpg[/img:e24689c36b]
Also the genteleme on the Toyota service told at sometimes it is enought to drive the car while with lower gear and with high revolutions so thse oxycen sensors will burn clean, so I dit. Also I replace the air filter which was dirty and also spark plugs are replaced. After all these the MIL light stll goes on. What I can do next?