Performed some diagnostic tests on the various sensors to try and pinpoint the dreaded EML. Discovered a lazy Lambda sensor which was giving an almost permanent lean condition so I took it out and cleaned it up by soaking the tip in Gunk degreaser then scrubbing with a toothbrush before rinsing with some water.
Put it back in, left it disconnected for the time being and started the car. Set the engine speed to 2000rpm for 5 mins to dry the sensor. Switched off and reconnected the lambda. Started her up and the lambda is now switching between rich and lean conditions very quickly indeed.
Unfortunately while doing this a small section of rubber hose (approx 3") which goes from the heater matrix to the head burst showering the engine bay with steam and coolant. I had a look at the donor car for a spare and would you believe its one of two hoses the previous owner had cut to get the head off

New one on order ($1.75) and should have it by friday. It is a different size at each end unfortunately so I couldnt replace it with anything I had in the garage.
Just glad it happened in the garage and not while out somewhere.
On a side note about Lambda sensors. I found a web article
HERE that said a lambda sensor takes a reading from the exhaust gas and the outside air. I have never heard of this before so gave the outside a good clean with gunk as well. At the end of the sensor where the wires protrude there is a ring of small holes around the sensor, whether these are for testing the external air or not I dont know but would be interested in hearing your info on this.