I would put a new CTS in as a matter of course, to start with.
This is the main factor governing the co, so needs to be right.
I did a festa last year a r reg one(1.25 zetec se) that was one of the damaged ones from Tesco petrol, and had been like it a few years, only a new lambda on that DESPITE it showing correct on gagues/metres, was switching way too slow, wasn't able to check speed with what I had at time, so took a chance.
tabetha