how to fix my fiat punto?

Try some redex fuel injector cleaner it's about £5 and worth every penny. You may have small particles from the fuel tank partially blocking the injectors. Which is why you only feel the lack of power when putting your foot down hard i.e accelerating from lower speeds. I will then seem to ease at higher speeds when you're not pushing it as hard and the engine requires less fuel. It takes a few miles to clear it, but you'll know when it has. ;o)

Moz
January 2007