cant rev pass 2k. maf? fuel?

my 240 is not getting enough fuel..

i can drive a max of 5mph then my car bugs out/gives up on the acceleration (engine still stays on)

i do have a fuel pressure regulator.
and i just changed fuel pumps recently (used) so im not sure whats goin on.

i unplugged my maf and revved but still same problem. i got a new maf. still the same problem... its acting similar to when my fuel pressure regulator was messed up... and i replaced that with an adjustable nismo one. but i dont have too much knowledge about how the PSI works so i dont want to do anything dangerous that i dont know about..

but maybe my fuel pump is messed up? or filter?

help/opinions would be highly appreciated.

Try cleaning your maf with carb cleaner (short bursts of spray)

Change your fuel filter, check your spark plugs (fouled out, gas on it, oil on it, white diposits, damaged, etc), wires, any injectors leaking?, check all your connections (maf, injectors, fuses, etc.) make sure your fuel pump is working, hope it aint your ecu.. You should have bought an oem fuel pressure reg.

What year is your 240?

At idle, the pressure should be approximately:

235kPa / 2.4 kg/cm2 / 34 psi.

Disconnecting the vacuum hose, you should see:

294 kPa / 3.0 kg/cm2 / 43 psi.

and you shouldnt have bought a used fuel pump. never good news. thats a part i wouldnt skimp on.

Check engine light on or off?