My Yamy is coughing

[ShrimperTony]

I have a 1998 T50 4 stroke Yamaha that's been the best motor I ever had by far. But now when I start it the rpms need to be at 1500 just to stay running.
Lower or higher and it coughs and stales. If I allow it to run at 1500 it will do so for about 5 min. she will go up to about 2000 rpms by herself, cough and stall.
I have changed out the fuel to ethanol free, added "Sea Foam" to gas, drained all 4 carb bowls and flushed with denatured alcohol, change out plugs and kicked my boat 5 time. Still the same problem. Any ideas?

[madharchod]

i would be synchronizing the carb as if it runs and coughs then its the fuel

[99yam40]

I have changed out the fuel to ethanol,

I would be getting the carbs cleaned not just flushed.
Need special equipment to sync afterwards so find a good Yamaha shop close to you.

never hurts to check the basics 1st
compression/leak down test, spark, and timing
Ethanol is for drinking not running a boat motor

[ShrimperTony]

Thanks. I agree with your ethanol for drinking statement. I miss-typed and didn't add the word "free" after ethanol.