50 tlr Motor Problems

Have noticed that when i go from 5 mph (15%) throttle to +80% to get on plane that my motor seems to have a loss of power and stalls at times. When i go 10 mph 25% throttle then go to get on plane it runs fine. I changed the fuel/water seperated and it ran like a top for the next 4 hours now it is stalling again. This boat has 18 hours total on it. What else should i look for before taking it to the dealer?

[jb123]

water,junk in your tank.
drain bowls, change motor filter.
do you use an additional water seperator?

I have looked at everything I can the gas tank and line look clean. Fuel / water seperator had clean gas no debris like last time no water ( I was told that water and gas will seperate in a mason jar) fuel filter in the motor is clean no debris. What should I do next?