Have a 92 waverunner 111 650 yamaha. Was running it all day, ran fine. When I felt a change in the engine started running rough and loss of power on top end. Not the same get up and go. Checked gas and oil, Oil was fine and put in more gas. Took it back out still ran the same, rough and loss of power. Took it home and changed spark plugs. Is there anything else I need to look at before I put it back in the water. I could use some help don't want to get it back in the water and have it get worse or damage it more.