NALEEN

hi Guys I need your help to sort out a Agony. i have mazda 323 Lx 1300cc carburetor engine yom 1995 I have very poor fuel consuption 7-8 per liter what are the possible problems with this ( i can grantee this is not because of my driving style ) I tried with several mechanics but still not done. When i swtch on Ac i'm getting serious Jerk and still no one able to find the reason for that . Please help me on this cheers