Plug wires Cap and Rotor, vacuum leak, fuel filter(delivery) when injectors go bad they go bad, but a couple cans of injector cleaner wouldn't hurt. Having them cleaned professionally would probably cost more than buying some on ebay. Are they the light blue ones, if so they are 24lb injectors.
We get lots of weeds on our prop and stargazer will run at 4k rpms to pull the right speed, so anything weird like that can cause the boat to run at a higher rpm to achieve the same speed
spuddering is usually loss of spark power, engine timing, loss of fuel delivery, or a vacuum leak.
Good Luck