Why is my van juddering ?

[bri-on-1]

Hi all, i still have a problem with my 2.0 cu Aircooled. When i get to a constant speed it's juddering? i have put a new fuel line in changed the plugs dizzy cap rotor arm, new ht leads ect but still have this problem. I think it might be sucking in air maybe, i will be putting a new fuel pump on today to eliminate that. If it is sucking in air where is it most likly for this to happen? I have twin weber 34 ict carbs fitted. Any help on this would be great thanks.

[faggie]

are both of the electro magnet jets working correctly