this is may case: I use the p34 as a part of a fleet, in the airline program Onair.
In flight with an overweigt of about 300lbs and a speed reduced down to around 80knt the plane starts first to tilt left right a little before nose suddenly drops and plane looses height and recover after500-1000 feet drop in altitude this happens without any audiable warnig, Onair register this as a stall. I have belived this is related to plane actually beeing overloaded (according to EU regulation).