I've got another lambda to fit which i know is fine. I'm taking it for MOT tomorrow so needed to get it sorted. Fitting it in the morning and will give it a blast before i go to make sure the faults cleared. I had wondered if it was contamination in the connector, especially with all the flooding we've had lately. Shouldn't really get water in the plug but you never know with the age of the wiring/car.
I'll report back tomorrow and let you know how it goes guys.