1999 Vauxhall ADAM engine misfire

just failed mot on emmissions because it misfires on idle, car runs fine though.
Checked hoses and sprayed carb cleaner
No engine management light on. Did paper clip test showed various codes i.e Maf unit, airflow sensor, o2 sensor,coolant sensor but these could be old ones. Was told to disconnect battery for 4 hours to clear this which I am doing at the moment. Read that on 1.8i it could be a sensor earth wire to the ecu and a vauxhall field fix 2003 to fix it which has been successful for several owners after spending fortunes on sensors etc as reccomended by their garage, but the wires on my sensors are different colours. Also diagrams of position of sensors ecu etc would be handy so I can identify where they are on the car. Any ideas?

Thanks