We have a '70 mercury 1000 100 hp OB.<br />It idles fine, however, when in the water and when put into forward the engine either runs very slow or dies, however, works fine in reverse.<br /><br />We have had the lower unit rebuilt, replaced the cap, plugs and wires, new fuel filter and fuel lines.<br /><br />Fuel leaks from the top carburetor.<br /><br />Any suggestions on where to start?