Looks like you started this last year. If you changed the fuel lines I am going to assume you cleaned the water separator as well.
Also take your fuel selector out and clean or replace it, there is a good chance of the gooh from the grey fuel lines could have that plugged up as well.
Then the carbs, they will need to be pulled apart, at minimum the little filters in there will need to be cleaned. Personally while you have them off, clean and rebuild with new parts as needed. Make sure to do a pop off test.
Add in inline filter on the supply line close to the carbs.
All the above should rule out a fuel delivery problem, I would also do a compression check to see where that is at.
Miffer, I see your from Welland, by chance have you put Gales Gas in this ski? If so, dont do that anymore.