If it's reading rich all the time then I expect your lambda has failed.
These drop volts and therefore the ECU think's it's running lean and chucks in fuel.
You will probably find that on idle and cruise you are running about 12.5AFR instead of 14.7AFR.
http://www.gendan.co.uk/oxygen_lambd...reza_2.0i.html
Just pick the one that matches the connector you have (early or late classic) and gives at least the minimum cable length. Don't worry about the model description lists.
Or just get a 3-wire universal which comes without a connector and wire it in yourself.
I'm running a £30 universal in mine.