Hi Ambrose, those are my YT videos of the power valve. If you really want to see if your power valve is not functioning properly at the high RPM range, there is a very simple test. Disconnect your air line that goes into the power valve. Take apart your power valve and place the spring on the INSIDE of the bellows and put it back together. (leave the air line disconnected) This will force the PV to stay open all the time. Take it out for a spin and see if the engine works any better at high RPM’s. It will be sluggish out of slow corners, but that is fine for the test.
If you now have the expected high RPM performance, then you know you have a PV control issue. If it makes no difference at high RPM’s then you need to look elsewhere.
Perhaps an even easier option is to leave the PV as is. remove the air line that feeds it from the solenoid. Blow into the line and you will see the PV open. Without letting any air out, block off the air line, so the bellows stay full of air and therefore stay open for a couple of laps while you do your test. A couple of small zip ties, will pinch off the air line nicely.
You could also try installing your old PV if you have one, but that is more work than either of the suggestions above.