I've had the ski out three times previously with no problems. The only thing I did differently was change the spark plugs. Went out yesterday and it ran fine for awhile, but then for some reason it started running strange. With full throttle (or any other steady setting) the engine would not seem to make full (or relative) rpm's. It was smooth, but would drop off in power then come back up, and continue that way. We let it rest for a bit and then it seemed to run fine for a few minutes and then the problem came back. It's almost as if the fuel feed was being continually/intermittently interrupted. I'm not super-mechanically inclined, but wanted to ask people I trust before heading into the shop. Any thoughts?