Posted for "Matt Hapgood" <hapgoodm94@alum.darden.edu>:

 That sounds similar to my experiences.  I can often feel the autopilot
 change pitch a bit to maintain the altitude, and the result is a change in
 airspeed... or is it the other way around?
 
 Matt
 

"""
At 14500 in smooth and clear
 conditions, but with a 42 knot head wind, the TAS would slowly swing
 between 190 and 215 kts over a span of several minutes.  I could feel
 the trim changes since I have no autopilot.
"""