In your first post you state:
"We changed the fuel accumulator, pump, filters(several times), all the lines leading from the tank to the pump assembly,the injectors, and were going to try the in tank filter next"
I suppose that paying a trained tech (or doing the tests yourself) would be more expensive than this. In hundreds of fuel pressure leak down problems, I never charged more than two hours labor for testing. And never did I replace anything that wasn't needed. I'd say that the testing would have solved your problem for much less than the coin flip method or the "wow" it worked for me method.
I'm always glad to try and help someone do the testing themselves, but when the facilities aren't at hand, I am the first to say that you need to find a trusted craftsman.
Bosch Master, ASE Master, L1
33 years MB technician