What turbo is on it - T2 or T3??

I've had the same problem as this in the past checked everything and it ended up being turbo yet no oil in pipes and no play at all in the turine, shit seals.

Try the breater pot, if its O.E pot then check its breathing properly take all pipes to the sump etc...inspect and try new pot - BAILEY best with a escort rs turbo pot they are bigger than fiesta ones.

piston rings seem okay its producing them figures