I bought a fishing boat w/50hp johnson on it. It was garage kept, but sat unused due to the death of the original owner. I cleaned out the carbs and replaced old fuel with new. It idled fine with muffs on it, I put it in a lake and it ran ruff for about 15 min. then smoothed out and ran fine. When I lined it up to put it on the trailer it idled ALOT faster than it had whenI first stated running it. Any idea what caused it to idel faster? And what should I do to correct the problem? Any info. is appreciated. JD