I am not sure if this is what you are asking, but there is indeed an uncertainty associated with Gabor's analytic signal and EMD, for that matter.
The problem that Gabor's analytic signal (and EMD as a sum of analytic signals) tries to solve is to reconstruct the time-dependent amplitude and frequency components of an Amplitude/Frequency modulated oscillator. That is, given x(t), you want to reconstruct A(t) and f(t) (you can think of frequency or phase interchangeably) such that
A(t) * sin(2pi * f(t) * t + phi0) = x(t)
Now, this problem is underdetermined, in the sense that several different pairs of will satisfy your single constraint, which is "match x(t)". So you need to provide further constraints to arrive at a unique solution. Further, it may be impossible to speak about _the_ amplitude or _the_ phase of the oscillator x(t), but only about your estimated values.