  We continue the study of the variation of the $p$--modulus of a foliation
initiated by the first author. We derive the formula for the second variation
which allows to study $p$--stable foliations. We obtain some results concerning
codimension one $p$--stable foliations. Moreover, we derive the equation for
the critical point of the $p$--modulus functional of a foliation given by the
level sets of smooth function. We show the correlation with the
$q$--harmonicity. We give some examples. In particular, we show that foliations
given by the distance function are critical points of $p$--modulus functional.
