Hi i've recently fitted a zetec se head onto my duratec block on my 2004 1.25 fiesta, After a day or soo of running fine the engine mamangent light came on and the revs keep dropping to below 500rpm making the car and gas pedal unresponsive, its like it cuts out but with out the engine actually stopping? I've hooked up a diognostic thing to it and its gave me a code of P0172 System to rich bank1 Does anyone know what or how i can solve this problem? Thanks JohnBoy357

 

For some reason the mixture is too rich (too much fuel).
Have you done anything to fuel pressure or injectors or map/maf sensor?
What about camshafts?

 

Noo we havnt done anything all we did do was put new o-rings on the injectors but thats advised to be done anyway?