I have twin Mercruiser 4.3 and and all of a sudden the starboard engine is running at higher rpms than the port engine. At full throttle I'm getting about 4800 rpm on the starboard and 4100 on the port engine. I'm curious what would cause this, both engines seem to be running well and I don't feel a lot of pull on the starboard side, in fact my sync gauge shows that the port engine is pulling a little stronger. Thoughts?