Just purchased a hurricane deck boat with a 1993 mercury 150. took it out today 1st time and it will only run about 1000 rpm. push throttle fwd more and it bogs down. back off to 1000 and it runs good. I am no outboard mechanic but I have checked compression. all 6 are at or very near 110. new plugs. Could it be carb rebuild time? or is there something else I should look at. The oil injection has been removed and gas is premixed at 50 to 1 . Any help will be appreciated. serial of motor is OD198657