I have a condensing oil boiler that keeps sooting up and cutting out the flame
The flame is causing the problem of sooting. It should be a nice blue colour and your is probably a yellowy colour This can be a problem with a bit of a blockage in the flue, or the gas valve neds adjusting to give a cleaner flame, or the boiler is not getting enough air flow to the burner. You burn a mixture of gas and air, and lack of air can also ause sooting. Take you choice. !
Condensing Boiler Problems