Off-late I am noticing this in my punto 90Hp. On the highways, when I maintain a constant RPM say 2000 or 2500, the momentum dips at regular intervals. It feels as if the fuel supply is cut off for a second. I couldn't feel this when varying the RPM, also this behavior is not connected to the speed. in the city drive, I seldom notice this but on highways it is very evident. initially I thought this is because of the road, the car might have gone over a patch work or on slippery tar. But since it was happening at regular intervals like every 1 minute, i sm suspecting the Fuel Filter or the Turbo Charger. Any guess anybody ???