outboard motor

I have a 1991 55hp yamaha. I was on the water for maybe 10 mins the motor was doing fine, i came to a stop never turned the motor off but when i went to get on step again it wouldnt. I put it back in neutral and reved it and it reved fine. Tried to take off again and its like its not getting power. So i thought it was the carbs. Took the carbs off cleaned them and changed the plugs. Went to test run it and it got on step but still didnt have full power so i let off and tried to take off again but it was doing the samething wasnt getting on step like it wasnt getting power. So i bought a new coil thinging that was the problem. I can have the motor running and unplug the top cylinder plug and it will stay running but when i plug it back and unplug the bottom plug it kills. Is it normal? And what else could be my problem