a few years ago i had the same problem, it turned out the fuel tank had around 3 inches of sludge and water on the bottom and it had finally reached the fuel intake pipe, i changed the filter 3 times between the thurne mouth and my mooring at stalham, i had a spare filter but had to keep washing it out, the engine would run for seconds and sometimes for 30 minutes, was your filter dirty when you took it off
the beauty of ranworth is the broad itself, the pub, well!!! no better or worse than any other broadland pub, there is water and power available also the ability to walk your dog, i do not stay overnight, too many disturbed sleeps,
drop the mud weight opposite the staithe on the far side and watch the world go by, bliss