I have 94 sea ray with a 350 mag and the engine has a miss. I changed the plugs(one was bad) and the fuel filter(which was clogged with crap). It runs better but still not right. There is a small peck at idle that you can hear in the second video, but goes away with any throttle input. I put a vacuum gauge on it this morning and this is my results.
There is a small amount of "blowby" coming from the pcv valves. thoughts?
http://i868.photobucket.com/albums/a...d/634fe181.mp4 http://i868.photobucket.com/albums/a...d/07750509.mp4

There is no PCV valve on your engine.
I suggest a compression test (not a leak down test). You should have around 155 pounds in all cylinders, warm engine. You may need a valve job if an exhaust valve is not seating. Don't skimp on the valve job. It is the most important part of the engine!
Dennis Moore

is it possible that the fuel filter being clogged caused a lean condition and galded or burnt a piston? here is the #2 plug. the rest of them were clean as a pin.

Fuel injected or carb? If its EFI one of the injectors might be flowing poorly or have a poor spray pattern.

a compression test will tell you if every thing is good, a melted piston will just always be dead, a constent miss at every rpm

its a carb engine, 4bbl weber. its running on all 8 now, just a little rough. I have a cap/button, and carb kit ordered for it. I'll do the compression test in the morning.