Hi all, this 1999 Range Rover V8 4.6 litre has a high CO reading of between 4.5 and 5.5 percent but only at idle. Fault codes(using Launch x431) were"mixture adaption factor FRA bank 1","mixture adaption factor FRA bank 2". This high CO reading happens about 90 percent of the time, other times everything is perfect, however at all times as soon as you lift the revs above 1400 mixture is perfect with very low CO readings and lambda sensors switching perfectly. At idle when the problem occurs both lambda sensors sit at .8 volts. The air mass meter reading at idle was 37.75 kg/h and at 2000 rpm was 60 kg/h. I removed and cleaned the Bosch hot wire sensor with carb cleaner and have tried adaptation reset a few times with no luck. The scanner is showing that the lambda sensors are getting their electrical heat ok and the heater resistances are both good.. All other sensor readings are good and there is no running problems. The fuel trims are showing at idle as 0.75:1 and at 2000 rpm are 0.85:1. Am wondering what my next move should be?