Mercury outboard 2004 140hp v6

[Robmac]

I have a mercury 2004 140hp saltwater series carb engine. Was having troubles with it not haveing spark on cylinders 3 and 6 found the trigger had cracks in it so i got a used one fitted it. Ran ok on all cylinders for a few minutes then started to miss again found wasn't running on cylinder 2 . Then turned it off noticed it picked up for a few seconds before it turned off so i started it back up turned the key just before it turned off and it ran fine on all cylinders could notice it pick up and idle fine . I thought it was a bad ignition so i tried another control box did the same thing. Anyone know what it could be ? Was thinking maybe i got another bad trigger as it looked like it could have been sitting on a shelf for awhile.