In my PA-28-161 (Warrior II), I occasionally get stumbles, both with my
old and new engine. Like you, I usually notice them in turbulence.

My guess (I don't have enough expertise to call it a 'theory') is that
the problem is actually a momentary change in the plane's angle of
attack due to turbulence. Since the Warrior has a fixed-pitch prop,
the RPM will drop when the AoA becomes higher. When the turbulence
goes the other way, you should get a power surge (as if the plane were
in a dive) -- I think I remember that as well, but I'll have to keep my
eyes open.

Does anyone have a better guess?


All the best,


David