mercury 150 EFI rev problems

#1
Good Day
We were out on our fishing trip and the motor ran great the first day
the second day i was having problems with revs , it would go to 3000 rpm and start shuttering and bogging down .
thought it could be water in fuel so cleaned out fuel filter added 2 bottles seafoam to 25 gal gas and ran motor.
No change
Just ran it a 3000 rpm for the week when traveling . we were trolling and motor stopped and would not start
10 minutes later it started again and we went back to cabin.
Talking to the guy tat ownes the camp he thought it could be a coil and the temperature affected the motor and shut it down
we trolled with the cover off and no more issues
Now we are back home and I want to fix the problem any suggestions?
Thanks
Lutz