Hi . This might help I have 96 tarago, have some problem like yours , you right with the oxygen sensor,I change them both 2 and another thing is fuel pressure,the fuel pump works but usually its worn out,low pressure keep you pressing accelerator hard, very noticeable on the hill have to use 2nd gear(auto) I'm drivin with it for couple years till it really dies on the road, After changing fuel pump I notice a big difference in power and fuel,idling should be 750 to 800rpm, if not, you running on open loop, clean your injector , throtle plate, also pcv valve. Good Luck