Is there anything else done with the car - mods, replacement parts, etc? Have you tried pulling codes? Not that it might produce any with the car running, but it's not a bad idea to check anyway. How are you measuring fuel pressure?
Those questions out of the way, it could be a few different things. Bad hose somewhere, clogged fuel filter (I realize you said it's been replaced), weak pump, kink in a line, etc. Unfortunately, we probably won't be much help until we know more. And pics are always a good thing, both of the car (because everyone likes to see what we're dealing with ) and of whatever trouble area you may be dealing with (because everyone likes to see what we're dealing with).
You are going to need to post your questions in full sentences and paragraphs with detailed descriptions of what your initial issues were, what you've done so far, and what your current symptoms are.
There are no crystal balls on this end that tell us what it is you're trying to describe.