We just had a similar problem on here with static fuel pressure changing after setting it with a new regulator & pump . Turned out to be the short hose , in-tank from pump to sender . You need FP readings while driving , if the pressure is dropping off it will show as soon as demand increases , as in 1 , 2 , 3 , 4 psi of boost . Remember 1 for 1 , boost & FP .
Where are you located , maybe someone near by could help . Sam