Fixed#
Thanks to all who posted and highlighted some issues with my knowledge of exhaust gases which i shall be addressing.
Went back to basics with this one and load tested heater wire earth on the 02 sensor which showed it as open circuit. Originally i provided this with what i thought was a good earth but there wasnt any current draw still but i now know that the earth i provided was no good! Whoops!
Anyway repaired earth and current draw shot up and the sensor began to switch perfectly! went straight through the emissions test with flying colours. Im still surprised that the vehicle could overfuel that much just whilst being in open loop with a respectable injection period?? Also the fault for the idle switch has not returned so must have been caused by the high sensor signal. Thanks for all the insight. Luke