Thanks Mario and Tim, just changed the brake pressure
accumulator (bomb) suspecting that was the cause but
with no result, should of mention it of course, sorry.
Had an 87 5000 and had the same trouble, so I was
confident thinking it is the same and went for it.
Something was suspicios when opening the "bomb"
lines, had good remnant pressure on the return line,
but nothing on the" in "from the pump line.
Could it be the pump is acting and supplies no pressure
to the bomb and thus the bomb syndrome?????