Troubling p0456

Have a 2008 Ram 1500 with 5.7 L Hemi

Truck keeps throwing p0456...

There is a new mopar gas cap...
The truck was smoke tested...nothing
Was told that purge valve was ruled out.
I've also changed the EGR Valve twice now and the PCM last year because it was malfunctioning, i.e. burnt 4WD and likely the EGR too.

Something of interest, when the tank is filled, it almost always spits gas - even when filling on slowest setting.

I need to pass emissions and need to hopefully resolve this without lots of expensive exploration. Anyone have any thoughts or does this sound familiar?

Thank you.