lads i have a golf iv 99 in garage and when idling it vibrates like mad.put it on o2 emissions machine and co 10.50% and hc3500 which is serious overfueling.Tried a map sensor and this cleared up the problem for a day ,then tried a throttle body which made no difference and only fault showing in ecu is sensor o2 fault. Am i looking at ecu fault or am i missing something:banghead:

the 02 sensor determines mixture preperation, bad o2 sensor means engine runs in limp mode and floods engine. Replace the sensor

there is a recall for the fuel delivery on that vehicle.