2003 Vauxhall Astra Car stuttering at constant speed

Hi,
My Astra has developed a stutter at around 2500 rpm when travelling at a constant speed and when you are just feathering the throttle, it acts almost like running on kangaroo juice also the engine warning lights comes on when the tank is running low. If I use a higher octane fuel the problem is less pronounced. I am thinking fuel filter or fuel pump? Any advice would be apreciated
Thanks