hi peeps, got a problem with my focus, i replaces a brake line 3 months ago and had to take the fuel filter of to gain access . Then 2 weeks later the car started running sluggish and the revs idle now 700-750, but when i put my foot down on the gas whilst driving the engine popps and farts then the engine runs fine and goes like a bullet also noticed that now when i take the fuel filler cap of there is alot of excess air comes out...any help will be very welcome