I know mines not a Fiesta but its running OFAC so its sort of a Fiesta lol

Basically every time I take her out and it geets up to normal temp and I igo off for a drive, I put the clutch down and the revs start to die, then it cuts out

As soon as I start it again it idles fine...

Anyone got any ideas?

I'm thinking a sensor gone down but I'm not sure where to start, anyone else had the same prob?