Sounds like you might be getting some channeling. You should get a nice even extraction (ideally) where the coffee drips and forms over the entire pf/basket and then becomes a steady stream.
Channeling occurs when you get a path through the puck that offers less resistance and coffee sort of 'explodes' out of the puck causing it to spray.
Sounds like you have tried a few things with little success. Maybe try being particular about how you pack the basket. So tamp as evenly as possible. Try the Weiss Distribution Technique (or another distribution technique) to loosen some of the clumped grinds.
It's all about getting a nice even puck so the water flows evenly through the coffee and gets a nice even extraction.