2007 excalibur misfire

Boat 2007 sn 206 ex330 with around 400 hours.
Ever since the test drive Julio boat is been experiencing a slight miss, more upon take off and when cold,
like a small hiccups.
Right after he bought the boat he had it serviced, fluids changed, along with spark plugs...problem persisted, mechanic went again and said a bad cable to the dizzy was going to ground causing missfires...
Engine got better but still misses some.

Last weekend he ploughed the bow letteing lots of water, some got into the bilge.He let the boat outside.
Sunday when he went to start it again engine was full of condensation. Ran the boat and missfire were terrible...but went away once the engine got warm...

At bf speed boat perform ok but if you lift the hatch you can hear the miss...

Cables are original, so are cap and rotor...
My guess is any of these 3 things...

Thoughts?

are there risks running the engine in this condition?
like burning a piston or valve or whatever?

Cris

thanks for the info, anyway parts need to come from the US, so paying extra for marine isnt quite an issue...
No local auto parts store carries V8 parts...our cars are european style with the little 4bangers...
Even for my vette I need to order parts from you...

Gary, they had a run of bad distributor caps about that time. You can do automotive, but I prefer to buy the upgrade ones with the brass contacts. I found them at O'Reily Auto parts.
Art

I'm glad to hear that it turned out to be something simple. No doubt the plug was cross-firing with another, and thus the erosion of the plug.
Art

Andy, I think that Kapla's problem was solved back in April. If you continue to have the problem, the following might help you.

True that the cam retard setting might be the cause. Check it as described. If you don't have access to a Diacom diagnostic system, at least check your engine serial number and specification decal against the information in the bulletin he mentioned.

Once again, the distributor caps can be a problem. Try to find the one with the brass contacts, not the aluminum.

You might want to check the resistance of the spark plug wires with an ohmeter if you have one. Resistance should be between 40 ohms and 10,000 ohms per foot, depending on the type of wire you have.

Make sure that the porcelain insulators on the spark plugs are clean. Try running the engine in darkness and look for any sparks around the wires, especially around the boots at the distributor end and at the spark plug ends.

Look at the spark plug electrodes for signs of abnormal performance on one or more plugs. Change the spark plugs and see if that helps.    

Nice looking boat Andrew!