my golf 1.4i 2003 is consuming alot of petrol ,1lt for 5km?

i have change the spark plugs ,the petrol pump,fuel filter,air filter change the oil.
the golf is using unusually alot of petrol. I use to get 11km to 1lt of petrol. at the moment im getting 5km to 1lt of petrol . could it be the throttle body .
the car is ruining me please help .