just cured similar problems on my focus 1.6 52 plate and my friends code reader said that i had some fuel level malfunction and that both my exhaust sensors were f**ked, so i replaced one and cured half probz then replaced the other and cured all problems ...
My problems were miss firing and lumpy at idle, lose of power when put my foot down (but not at high speed, 70mph) then power would cut back in, also have you checked your gaps. i cannot remeber what the codes were, sorry