94' 4.0L Ranger

banghead: I need some help with codes 181 & 189 . The reader book says that these are both problems with the HO2 sensors. It says cannot shift lean at part throttle. My Chilton book says the same thing but words it as being rich on both the right and left sides. I have changed both O2 sensors and I am still getting the same codes. If anyone has any thoughts please let me know.