You have once again missed my point…. If you have replace all these parts why not replace a 12$ easy part??? The components inside can brake down and clog the ejectors,carb and regulator and you have wasted your money and time…
You could throw parts, time, and money at the problem, or you could perform an injector balance test and see if you have clogged or sticking injectors.
maybe the fuel filter might need to be changed anyway, who knows.