Carburetorated engine running rough after day on lake

[bucklahoo]

Newbie here. 83 Mercruiser.
Just had new fuel pump installed & fresh gas. Engine starts up and idles smoothly at start. Idle out to Lake and stop and go to fishing spots we have no problem but when we get back to the no wake zone channels we start running rough almost wanting to stall at points.
My research says maybe choke or vapor lock? Maybe carb cleaning (haven't specifically done that)?
What would be a good place or procedure to start diagnosing? Thanks

 

[Grub54891]

Is this a new to you boat? And if so, how long did it sit before you got it? And how about a model/serial number of the motor? If you just aquired the boat, we can diagnose with a few questions.

 

[Scott Danforth]

May be your choke

Not vapor lock

Most likely crud in carb. Time for a tear down and go thru the carb

 

[Lectro88]

If its set a long time, Ethanol could have struck again.
You could have a little ignition problem, or some of both and several other little gremlins.
Sounds like you ran it just enough to break a little goop loose in carbs.
More below.
I myself try to only run Eth. in daily drivers, Never in lawn equipment or small 2 cycles(chainsaws, weed-eaters, blowers. Etc. (they can sit too long)

Grub54891 & ScottD Got the first part of the question covered.​

Plenty of help available on this topic.
Just don't get your hopes up that it is a 1 and done problem..
I say that because my neighbor and I spent 2 months chasing our tails and finally took to dealer/marina, this is the 4th trip and its been there over a month now and still not fixed.
Not to brag, but I have wrenched on land motors 40+ years and this thing made me feel like a flunky. But I'm better now that a boat Dr has called Merc. and they are fumbling too.
Changed stator, trigger, several coil packs, checked timing and I went through carbs 2-3 times. (knowing they were clean,.. carbs are nothing new to me) and still scratching..
Not that this would happen to you, but it does happen.
It was also a new to us motor, so history unknown to add to the mix.

 

[Grub54891]

As suggested, more like a fuel/carb issue. But I've also seen the weights in the dizzy under the trigger plate go south, timing will be affected. Just another tidbit to check out when all else fails.