90xr,
I had this same problem this past spring. Since you already did the relay and pump test, go ahead and bleed the brakes. See if that helps. If not, do the driveway test to determine if your accumulator is working correctly. This test is turn the ignition to on, but don't start the car. Listen for the pump to start and shut off. Once it shuts off, pump the brake pedal until the pump starts again. If you press the brake pedal two or less times, then your accumulator might be going out. Mine only went for two pumps, so I changed out the accumulator. I did the driveway test again and still had the same results. Only two pumps of the pedal until the pump started again. So the only thing it could be was an internal leak in the master cylinder, or I think it's the main bore cylinder. Anyway, I sent it off to Prior Remanufacture, you can look them up on the WEB. They had it rebuilt and back to me in 10 days. Cost about $450 I think. Try the driveway test.
Hope this helps, good luck.
Greg