Thanks everyone for your help. Bucking problem is fixed. I had the fuel pump and filter replaced. My problem was when the gas tank is below half, the car begin to buck badly. Another problem solved!

Birthdate 1/6/2000 Mods: 35% Tint Bosal Exhaust K & N Air Intake, MAF Koni & Eibach Spec I/Spec Flywheel DMD http://www.villagephotos.com/pubbrowse.asp?selected=895138