60 hp 4-stroke EFI Bigfoot 'misfires' erratically

[Paso Pete]

This is a newly acquired '08 motor with about 65 hrs on it. Seems to run a little rough, but starts right up and 850 rpm idle not super smooth.. WOT sometimes produces rpms to 5600, but most of the time WOT only produces 4400 rpm, with unresponsive throttle past maybe 3/4 Sometimes it is running at 4000 then rpm's jump to 4800. Sometimes rpm's drop 800 or so. Changed plugs even though they seemed to be burning ok. Changed lo pressure fuel filter, dumped old fuel and added stabilizer to new fuel.. When it changes rpm it is very sudden.
Trying to figure where to start - fuel or spark, or ground ? I originally thought i had a prop pitch issue, but its clear its engine related.
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Appreciate any suggestions and thanks in advance

 

[Paso Pete]

OK - I didnt get any responses here. However, I was able to find and fix the problem - turned out to be one of the coils. Surprized me because it was an intermittent issue. Found it by pulling each plug when running - identified 'dead cylinder' as #4, replaced plug - still dead. grounded coil wire - no spark. Then I switched the coils from #3 and #4. Now dead cylinder was #3. Put in new coil today and it runs like a champ.
I am posting this as hopefully someone else with similar issue may read and this helps them fix their issue.

 

[wneill20]

I want to Thank You i have been fighting this issue for weeks, After reading your post it sounds exactly to what is going on with my 2008 60 HP EFI and i have ordered a coil. Lets hope it solves my issue also!