Long story short I had an auto electrician out to sort some bits and Bob's, afterwards my idle was so rough , hunting so badly but never stalling but drove fine, noticed the other day that the lambda plug was unplugged (thought he forgot to put it back in) so have plugged it back in, ran fine for 20mins then started idling really badly again and stuttering in every gear and slight loss of power, so worse than with it unplugged.does this mean I need a new lambda sensor?