Usually flutter, particularly elevator flutter,
is a faster oscillation, many cycles per
second. The airplane doesn't usually
react this quickly so mostly you don't
see drastic changes in attitude.

Spotty contacts in the servo potentiometer
can make it do wild swings that would
look like the symptoms I'm reading. I
would not expect this on multiple servos
only installed on the elevator over several
years.

I could understand such symptoms if the
flying was done near the edge of a cliff with
wind blowing towards the face of it. Weird
eddy currents would occur downwind of
the cliff. This would affect all flight attitudes,
but could really exacerbate a tail heavy
condition.

Other things like houses, barns, and large
rocks could also cause such eddy currents.
Sand dunes could cause them as well, but
mostly closer to the ground. When there
are multiple obstacles to the wind in close
proximity to each other their interference
can cause some really strange wind
patterns.

Jenny