Volvo penta fuel surge

[Pete Bowler]

Hi all
I have a 18hp Volvo pentagon in my 33’ yacht
Recently it has begun to play up a little.
A few weeks ago it would cut out a couple of times at or near idle but ran fine when at high revs
Today it did similar but worse
There was no wind and I had to motor for about 45 minutes to return to mooring
It ran fine on the weekend and for maybe 20 hours since previous problem mentioned
But today after about half an hour of earlier running it kept cutting out
The best option I found was to run it about 1/2-3/4 revs and when it wanted to cut out I gave it full revs for a short period then settled back to previous revs
Looking for any ideas of where to start trouble shooting
Thanks