Need help with porpoising

[jl8200]

I used to have a boat similar to this. I was a 17ft Alumaweld with a 115 Yamaha on it. I bought it with a wale tail/hydrofoil thing on the motor and it made a huge difference in porpoising. How do i know this? Well the first thing i did when i got the boat was take it off and it ran like ****. I put it back on right away and never took it off again. The boat just ran better with it on. Maybe that might help.