As for timing........your boat will be happier with about 20 degrees initial and all in at around 32-34 by 1,800 to 2,000 rpm.

When I said timing, I was not referring to the total timing number. Instead, I was referring to are you getting your advance in soon enough and are you truly getting the full advance. I've seen too stiff of springs, sticking advance weights, too high of RPM before total timing is in, etc. cause problems like this that at first glance could be writting off as fuel problems.

To add the this timing discussion, it really depends on your heads and intake configuration along with your static and dynamic compression and fuel used.

With that said, I make most power with 28 degrees with trick flow heads and an efficient intake on 93 octane, and I just keep it locked out there.

on the timing thing,the vortec heads dont like a lot of timing,i would stick to 30 or 31 total advance but bring it all in by 2000 rpm,i am leaning twards it being a adjustment of the acceleraror pump.

I have been swamped with work and havent had a chance to get it in the water. I did bump the accelator pump to the next hole. I am also planning on checking my timing in 500 rpm increments just to be sure. I really think I have a carb issue. I rebuilt the edelbrock 1409 from top to bottom, and the idle air mixture screws make no difference. When you screw either of them in the motor stalls, if i unseat them to all the way out, the motor runs the same. The mixture screws did the same thing with the stock 260 also. I am leaning toward maybe having a quick fuel technology mechanical secondary carb built for it.

No I understand what you are saying, but I've seen some Merc EFI motor timing tables and the amount of advance at high MAP and lower RPM is often less than 28 degrees and the motors run fine, which would lead me to believe in this case it's fuel. More often than not the carbs are the culprit due to their complexity relative to the ignition system.

I wish it was EFI. I dont mix with carbs.

I hear you. This is somewhat off topic but I'd get a wide-band O2 installed so you can really dial the carb in and know what's going on. It's obviously necessary with EFI stuff, but if I ever do a carb motor I would absolutely install a wide band to take out the majority of guess work or plug reading. I'm a carb dumby.

I ran the boat yesterday. I did not bump the timing up yet, but i did move the accel pump rod. It help alot. There is still a small bit of cough. There is also what feels like a miss at part throttle from idle to about 3750. After 3750 it runs smooth as silk with much healthier feel. I dont have power yet for the electric choke. So I turned the choke so it is always open. Could that cause an issue?

I have an edelbrock carb and do not use or have the electric choke wired either. I have it cable tied in the full open position. If it is not tied in the open position it will move and you could be choking while your running.