[DanEC]

There seems to be some conflicting data there - in one place you said it runs about 6 psi at idle with mechanical or electric pump. And later it idles and cruises at 9 psi. Or did it used to run 6 psi in past years and now it's running 9 psi?

I assume this is a mechanical fuel pressure gage? If your pressure is falling off to 2 - 3 psi at 3000 rpm you either have a mechanical pump going bad or some restriction somewhere. Also, possibly your tank or cap is not venting and it's taking the electric pump to pull it from the tank and push it to the engine. When opening your fuel filter do you notice any pressure being released?