Ford Escort - 97 1.8 failed MoT on emissions - high Lambda readi - RattleandSmoke
Different engine but we had a 1.6 Zetec Escort which failed on the same thing. The garage then just gave us a dodgy MOT instead (they used another car). My uncle then had a look at it and came to the conclusion that some of the valves were sticking.
I don't know what the readings were and it may be a completly different problem but those Zetec engines due tend to suffer from sticky valves if the wrong oil has been used.