Are you censoring? I don't see any '-regress_censor*' options in what you had placed there.

If you really are not censoring, then you could use 3dRSFC on the output time series to calculate ALFF, then. (However, you shouldn't trust the fALFF results, because the non-LFF frequencies are already removed.)

And, again if you are not censoring, you could use the -regress_RSFC option within afni_proc.py directly estimate by ALFF and fALFF during the processing (in that case, you *can* estimate fALFF, because the amplitudes of the full spectrum are estimated before bandpassing at the very end).

from the afni_proc.py help:

-regress_RSFC           : perform bandpassing via 3dRSFC

            Use this option flag to run 3dRSFC after the linear regression
            step (presumably to clean resting state data).  Along with the
            bandpassed data, 3dRSFC will produce connectivity parameters,
            saved in the RSFC directory by the proc script.

            The -regress_bandpass option is required, and those bands will be
            passed directly to 3dRSFC.  Since bandpassing will be done only
            after the linear regression, censoring is not advisable.

            See also -regress_bandpass, -regress_censor_motion.
            Please see '3dRSFC -help' for more information.

But it would be good to be clear about your processing steps first.

--pt