Ok, 06 Fiesta 1.25 Style. Seems to be SUBSTANTIALLY down on power until the engine has warmed up (sister's observations, not mine). Any ideas? Possibly choke playing up?
The closest thing would probably be the engine temperature sensor (not the one that necessarily feeds the instruments). Plugging it into a fault reader might tell you if it has failed. On the other hand, it may be cheaper just to change it.