Chrysler 45 intermittent power loss! (and suzuki 140)

Hi

Went out today in my little boat and when coming back in towards the harbor the engine cut right down and slowed from around 20mph to a crawl. every 5-15secs full power would resume but only for a second or two. Any1 know what could be the problem here? because engine either has full or very little power i get the feeling a cylinder is cutting out. my first instinct would be that it may be the coils or spark plugs??

This exact problem happened last weekend out my other boat, a 140ph suzuki, which i have still not resolved.

I havent had a chance yet but i will check the spark plugs and also fuel filter.

Has any1 had a similar problem? any help would be much appeciated

On a similar note, how can i check the coils are working properly??

FYI:
the engine is late 70s, its a 2 cylinder 2 stroke with single carb and twin coil packs.
The Suzuki engine is a 4 cylinder 2 stroke with 4 carbs and 4 coils.

Cheers

Check the compression/spark first.
Then start at the tank:vent line and then hoses.The squeezie,replace and any inline connectors,remove.
Fuel pump diaphram.Clean the carbs.J
Profile?? You might be close to someone who can help.J

Both engines? sounds like water in the gas- filled at the same marina did we? Loosen the carb bowl retaining nut and catch the dribble on a plate. Bet there is water in there some where. After cleaning the tank, you can clear the carb by putting the palm of you hand over the intake of the carb while running about 1200 rpm. This will vacuum all the crap from the channels in the carb. Then on a lower throttle setting, hold the butterfly of the carb open to "unflood" the motor. As the motor clears - let the butterfly close to avoid high -no load- engine speeds. Do it in front of your kids and they will think you the bravest man in the world.