1.9 Petrol jumps and jolts occasionally on long journeys?

[Kermit the Van]

On long motorway journeys my T25 occasionally jolts and skips. It will stop if i release the accelerator for a second then put my foot back down. I presume its a fueling issue, i did a basic rebuild on the carb and swapped out most servicable parts and it still happens. Anyone got any idea what this could be?

[maxstu]

Blocked fuel filter near petrol tank restricting flow?

[Kermit the Van]

Blocked fuel filter near petrol tank restricting flow?

Replaced the filter recently, seems to be fine. Van drives really well usually, just occasionally on motorways it will start sputtering

[maxstu]

Did it suffer from this issue before partial rebuild?
Sticking to fuel, there are two more filters associated with the carb... it's a pierburg, l presume? A conical one where feed pipe enters carb. And another cage at the top of the carb, often missing.
Only on motorways? Or above certain revs? Will the spluttering rear its head if revving at standstill and in neutral?
Carb float height incorrect?