Hi: I have an old 50hp blue band merc. that idles rough and will run rough even at high rpms but will smooth out while in the water with the lower unit engaged. It never fails to start and will idle fine although a little rough. It is on a 78 model Loweline flat bottom bass boat The boat is loaded with plywood decking and compartments which makes it heavy but very stable in the water. The motor will push the boat down the lake at 26.3 mph as noted on my GPS. Does anyone have any idea why it runs rough? Thanks
