increase current lm317
I think you're confusing the switching performance of power mosfets with their lack-of-advantages in linear circuits. Very small MOSFETs handle very large currents, but ONLY when operated in a pulse mode. That is, either saturated or off, never in the linear active region. I use a 75A MOSFET in a 25A switch circuit, and it generates less than 3W of heat. But if that same part were in your application, with 2.5V across it, it would generate over 60W of heat and immediately fail.
Infinity is an impractical design goal. What is the max output current you need to deliver?
ak