Car stuttering (sputtering?) While driving.

My car stutters sometimes while driving. The air and fuel filters have been changed, the fuel tank has been cleaned etc. Nothing helped. There are air bubbles going from the tank towards the engine, you can see some air bubbles in some of the little pipes under the hood, that is the trigger I think, not sure though.

The problem sometimes goes away for some time when the fuel tank is almost full and occurs again when it gets emptier. The car stutters while going, sometimes very minimal, sometimes harder, usually goes away after you put some more acceleration.

Also, "Glow plug warning" comes up on the dashboard sometimes while stuttering, sometimes it does not come up though.