could you go through the steps you did to check your fuel pressure.
as years ago i had the same problem u are having .
first i added a gauge to my fuel line, drove the car until the engine heated up (water gauge reads 1/2 way)
then parked the car,, next morning went out . ( with no other moves ,opened the hood) showed 591/2 lbs)
had my wife start car as i watched the fuel gauge i had installed . as soon as the engine started to spin
the fuel pressure went to 12 ,,,the second try the pressure went to 60 the car started . i replaced the fuel system with a manual fuel regulator with a return line with a check valve in going to the engine also added a new filter because the stock fuel filter and regulator are incorporated in one