74 1.8 - fuel pressure regulator?, opinions. Options

[wonkipop]

car = 74 1.8 L jet (all intact).

problem =
out driving this morning - gradual then worse loss of power. no accelerator response.
pulled over. cut out. no idle. let it sit for a few minutes. restarted it. got it going.
got up road all right, but symptoms kept coming back, then going away. limped it home.
fun ruined for driving, but fun diagnosing started.

felt like your classic fuel starvation.

background. car has been recommissioned and back on road for about 5 months.
running beautifully.
fuel system entirely rebuilt. clean tank. new fuel lines. new fuel pump. new injectors.
all vacuum lines renewed. all ignition compenents renewed. except coil (which could be original, looks like it, but coil was tested and was a goody).

one thing = fuel smell in engine bay on lhs around air cleaner. comes after a few days sitting. had put this down to saturated charcoal cannister, feeding back fumes into aircleaner. have inspected all fuel lines etc thoroughly and no signs of any external fuel leaks/wetness. just a vapour smell thats not there all the time, just after sitting.

pulled everything apart today down there after getting home today.
checked everything. all tight, no air leaks. no bad hoses.

looked at pressure regulator. which sits right there under aircleaner.
i have no reason to think its not original and about 45+ years old.
and did not get replaced. looks great externally, but.........internally?

will get car into shop this week. where i can get some guages on it etc.
at home with car. nothing but basic tools.

but whats thoughts out there.
anyone had this one before.