Hi Rick,
You are right, the grayordinate format is in NIFTI-2 format, since the output is:
n + 2 \0 \r \n 032 \n

I wish AFNI could support it now,,but, Isn't there any way like "ConvertDset" or anything else which can convert the NIFTI-2 format to the niml or 1D format (like what we use in suma)?

About the volumetric data, the 3dinfo output is:

Dataset File: rfMRI_REST1_LR_hp2000_clean.nii.gz
Identifier Code: NII_59c0ejyBA9NHV7EYfO9gGQ Creation Date: Fri Mar 7 13:01:21 2014
Template Space: MNI
Dataset Type: Echo Planar (-epan)
Byte Order: LSB_FIRST {assumed} [this CPU native = LSB_FIRST]
Storage Mode: NIFTI
Storage Space: 4,332,619,200 (4.3 billion [giga]) bytes
Geometry String: "MATRIX(2,0,0,-90,0,-2,0,126,0,0,2,-72):91,109,91"
Data Axes Tilt: Plumb
Data Axes Orientation:
first (x) = Right-to-Left
second (y) = Posterior-to-Anterior
third (z) = Inferior-to-Superior [-orient RPI]
R-to-L extent: -90.000 [R] -to- 90.000 [L] -step- 2.000 mm [ 91 voxels]
A-to-P extent: -90.000 [A] -to- 126.000 [P] -step- 2.000 mm [109 voxels]
I-to-S extent: -72.000 -to- 108.000 [S] -step- 2.000 mm [ 91 voxels]
Number of time steps = 1200 Time step = 0.72000s Origin = 0.00000s
-- At sub-brick #0 '?' datum type is float
-- At sub-brick #1 '?' datum type is float
-- At sub-brick #2 '?' datum type is float
** For info on all 1200 sub-bricks, use '3dinfo -verb' **

And as Daniel said if I use 3dcopy first, 3dFourier works well, but if I want to use it for the .nii, it terminates.

Thank you