Tohatsu 40D sputtering at mid to high RPM

I have a Tohatsu 40D on a MacGregor 19. It had been running like a champ until recently. It still starts right up and idles fine. The issue is when the throttle is at mid to high. The engine sputters/hesitates like it is low on gas. I have replaced the fuel line and new spark plugs. Any help is much appreciated. Thank you.

By "replaced the fuel line", do you mean the primer hose from the tank to the motor?
When were the carbs last cleaned? Do you idle the carbs out at the end of each day, or open the bowl drains and drain the carbs regularly?

Hello Paul,

Yes, I meant the primer hose from the tank to the motor. The carbs were dipped and clean this weekend. I am planing to take the boat out to test next weekend. The carbs were not dirty when I took them apart (no residual) but dipped them in the carb cleaner solution for a couple of hours, just in case. I do not idle the cards out or open the bowl drains (did not know to do this).

thank you

Wouldn't hurt to clean the carbs (properly), as you did. Also verify or replace the fuel filter element. With modern E10 fuel, and the limited run time most sail aux motors get, the fuel can sit in the carbs and evaporate, leaving a varnish residue behind. Since that would be internal to the passages, the carbs can look great, yet have transition circuit or other issues. Running the carbs out greatly reduces varnishing. Or, in the alternative, draining the bowl via the drain screw, particularly if the motor will sit for a week or 2 (or more).

Did you verify float height while reassembling the carbs? Is the problem a recent thing, or has it been there for a while (maybe slowly getting worse)?

Hello Paul,

Thanks you for your feedback. Much appreciated.

This was a recent thing just started about a month ago. It's been running fine for the past 2 years since I've had it. I've checked the float height after reassembly. I'll have an update after I run the boat this weekend.