My 89 Mariner 100 hp was not running right & also dumping fuel out the back.I put a new fuel/water filter,nylon fuel filter,new plugs, & rebuilt the fuel pump.Put new fuel hoses on also.Now it will not idle.You start it up & it idles @ 1200 rpm for maybe 30 40 secs & then surges to 1800 rpm & coughes & drops to 1200 rpm then back up to 1800 rpm & in one second it repeats itself.I have never put a carb kit in it.maybe I need to!I would like any help on this problem.I have always used premium gas.HELP...............THANKS!