Low fuel pressure reg or pump

Let me run this past the experts to make sure I am thinking right.

99 Venture, 18-20 pounds of pressure while running with new filter. It has very good flow, a solid stream of fuel.

It also holds a pressure test (if it can get to 40 psi once in a while) for 10 minutes.

I run at idle with 20 pounds and pinch off the return with no pressure increase at all. It must be the pump correct? and cannot be the regulator.

Everything else works good on the van. Is there slim chance it could be connector/voltage/electrical? It has been running bad at 1/2 throttle plus for a couple weeks. Runs perfect at below 1/2.

Rephrase question :

Is it the fuel pump for sure? I think so.

I got fixed up , it was the pump. For some reason I was under the impression that 50-60 psi was norm. The replacement pump has 38 psi and when WOT maintains 45 psi.

There must be a way that the regulator increases pressure as load increases. That's really the way it should be. I also found my reciept from the old pump, it was exactly 2 years old. The tank, and original filter was whistle clean.

I wasted $15 bucks on a filter that I didn't need. Oh well.

Funny acting symptoms that as soon as it went to 50% throttle, closed loop , and 0 short term trim it completely fell apart even though the pressure didn't fall off.

Which comes first? all 3 are related and happened at exactly the same time.