my head gasket gave out so i changed it and the cambelt when it was started it was missfireing and smokeing so i tried to remove the injectors one snapped off in the head and the price of 200 injectors is stupid so ive fitted a 300 head which runs fine when warm or after 5 mins from cold but forthe first 2mins from cold it has a mid range missfire and smokes ive tryed so other injectors but its the same ive also fitted new heater plugs any ideas ?