If there was water in the gas, you may not have it completely out yet. I’d consider having the tank dropped and flushed. Water will easily separate from the gas and collect at the very bottom, since water is more dense. It is probably underneath the fuel pick-up point, but still enough in there to continue to mess up the fresh fuel you keep adding. Gasoline will still absorb a certain amount of moisture, and it will dramatically affect the burn characteristics.
Once the tank is clean, consider a fuel system flush and a spark plug change. That should clear everything completely up for you.