@P90PC
Prior to be stating swapping plugs, is all well on the head gasket front.
Was the recall completed if required. Misfire can be a classic indicator of this issue.
If under warranty still,suggest letting the ford techies run diagnostics first
Hope its a simple fix and you get the smiles per miles of RS ownership.
Nitrous Blue – Forged Alloys – FMP375
Bugs on the windscreen and mud on the side
Now Enjoying the cooler winter air.