fickle classic 50

[bayrunner144]

I need some help with an unreliable Mercury classic 50. I recently purchased a 16 ft. bayrunner open w/ a 1989 45 hp. please bear with me, i know this topic has probably been beaten to death. I've read many threads and am still stumped. short version is sometimes it's hard to start and sometimes it's die at slow speed or idle but very inconsistent. runs great at planing speed. Now for the long version. hose and earmuffs it start easy everytime. submerged starting is sporadic. choke works fine. fuel was coming out of carb when squeezing primer bulb. took apart carb, adjusted floats, stopped dumping out of carb. when squeezing bulb, carb squeaks and if you squeeze bulb really hard, fluid shoots out economizer jet. carb looks like it was rebuild recently, very clean, new gaskets.fuel pump looks freshly rebuild(new gasket), new fuel filter. when on the water, the trick that usually gets it running are either to squeeze the bulb while cranking the motor or move idle lever all the way up. I need to know the most probable issue, check it and move down the list to the least probable issue. Your assistance is much appreciated.