New fuel pumps, new regulator, on idle I have 28 psi. , give it gas psi.drops to 22-25 psi, vacumn line unhooked @ regulator on idle I have 38 psi. drops down to 30 ,give it gas drops to 28-34 psi. anyone have any suggestions?

 

Spec is 30-40psi so not that far off

Engine should run fine down to 15-20psi

New fuel filter?
Some Rangers around '86 still used the canister type filters, picture here: Scianceplace-BII168.jpg Photo by flat-toy | Photobucket

And some had these near gas tank but no filter cartridge inside, they were used as reservoirs so the high pressure pump in the frame rail didn't run dry

What about with key off?
Fuel pressure should hold for a few MONTHS, not minutes, hours or days....MONTHS
If pressure drops to 0psi then you have a leak somewhere

 

I thought being EFI it had to maintain a minimal psi of 30, for injectors, when driving ,it bogs down and surges like fuel starvation, when I disconnected the vacuum line to regulator it did way better, only surged twice on a 30 mile drive.. Fuel filter is about a year old.. Even with a return line to tank it should hold pressure for months?

 

Yes, it should hold pressure for MONTHS

Outside of a leak in the fuel lines there is only 3 exits for fuel and fuel pressure

1. Fuel pump has a built in Check Valve, backflow preventer, basically just a hinged flap that is pushed open when pump is on and then pushed closed by the pressure in the system when pump is off

2. Fuel pressure regulator(FPR), it is a spring loaded valve, usually the spring is set for about 42psi, so at 43psi pressure pushes it open, and it closes again at 42psi
The vacuum assist is there to keep fuel pressure more stable, less of a gap in the range of pressure at the injectors
So with engine running at idle vacuum is high and fuel demand is low so with the assist the FPR is pulled open at about 35psi instead of 43psi
As RPMs increase vacuum goes down so less assist and pressure does drop as much because spring is able to hold the higher pressure in higher demand.

3. Fuel injectors, if an injector is sticking open then you would have lower pressure, but you would also have symptoms of Richer running, i.e. Rich O2 sensor codes, noticeable drop in MPG.

If you have noticeable signs of "running out of gas" then you probably are.
Your high pressure pump should be able to generate up to 50psi.

I would try this, hook up pressure gauge and cycle key on and off, fuel pumps only run for 2 seconds but do that EACH TIME key is turned on, you get about a 10psi increase each time.
So you should be able to build up pressure to above 40psi if FPR is working as it should.
If you can only get up to 38psi then I would replace FPR

It is possible the new high pressure pump can't pump higher than 38psi, which would indicate a problem, you could remove Return line from the FPR and put a towel around opening
Then do the key on, key off to build up pressure, if FPR isn't opening, gas coming out Return line opening, then pump itself is limiting the pressure.
If gas is coming out at 38psi then FPR is not holding pressure as it should

You replaced in tank fuel pump, did that include the "sock filter" in the tank?


Fords EFI system only Primes the fuel system for 2 seconds when key is turned on, and that adds about 10psi of pressure, so this would mean Ford expects the fuel system should lose no more than 10psi of pressure regardless of how long it sits.
And this is true, but just the example of why Ford thinks its true.

So key off you should see fuel pressure stay above 20psi, my 1994 drops to around 25psi key off and stays there, tested after 3 week vacation and it was still at 26psi