Merc 1000 idle issues

Recently I got a bass boat with an old 60s Mercury 1000 on it. After getting it worthy for water, because it was somewhat of a fixer upper, I took it out on the lake. It ran great but it didn't idle all that great. It would die if you didn't get it into gear and go quick enough. So I figured the idle screw just needed some adjustment. So anyways I took it home and tried to adjust the idle screw and it seems that I have to move it almost all the way in in order to get it to idle right. I have a feeling I shouldn't have to move it almost all the way in. The weird thing is that the engine runs good at all other speeds just the idle is not right. The other odd thing that I noticed is that even when the engine is cold the choke does not help at all. In fact it makes the engine harder to start and wants to kill the engine even more so then without. I was just wondering if I could get some help here on what I should start checking first. I haven't done anything to the engine except put new fuel in it. I was going to attempt to do the timing but my engine does not have a timing sticker on the flywheel like the Mercury 1150 does so I did not know how to do it. Also I figured I would do the plugs and clean the carburetors while I was at it but I wasn't sure if this would be the source my problem since the engine runs very good at any speed except idle. This seems like a very basic question but there is not much information on these engines. However on the Mercury 1150 some people attributed a week idle to a fuel pump that needed to be rebuilt. Possibly this is my issue? Should i just not worry about how far I'm cranking he idle screw as long as it idles?

What you should worry about is the water pump impeller shredding itself. It needs to be changed.

A flooding carb will cause all of your problems with idle and weird cold starting. Rebuild the carbs, then the fuel pump.

Timing shouldn't be a problem--they don't tend to change. I'd do the above first and worry about ignition later.

Jeff