fuel pressure dropping over time

I don't recall you saying if it has ever worked properly. I would bypass or open up the regulator and give it a whirl. My son had a similar problem where his truck with a 360 would fall on its face after getting into it. We found the fuel pump was bad & after replacing it all is good again. When we took the pump out, the pump arm had slop in it.

yeah, it works fine for the first 20 minutes or so
then temps rise, fuel pressure drops and issues occur (not saying they are all related, but they do show up together/at the same time


was hard to read, but enough info there for me to google it and find a bigger version
it does look like my filter element is about the size of bottom one in the last picture..not very big indeed