Throttle spikes while loiter, and make plane stall

Hi All,

What can cause throttle spikes in a plane?
So I was doing a mapping project, everything was fine when the plane doing automatic waypoint and Return to Launch.
After the plane arriving home, it’s loitering above the home point and suddenly stall. Fortunately, the operator has a good response and have control then landed the plane safely.

back to the office, I check the log, and there are 3 throttle spikes before the plane stall.

so, what is causing this?
here is the full log :

Thank you.

Throttle spikes happened after the stall, to try prevent stalling. Look at pitch and elevator.
Something was fishy before the stall, because with pulled elevator plane flown at ~8 deg pitch in level. Also during the whole flight elevator is pulled, perhaps a trim issue ?

Thank you for your input @Eosbandi , I will try to lower my elevator trim, this is a flying wing so it needs a little up trim. but it looks like I do it too much.

But, why my DesPitch is around 8 degrees, this means, the plane wants to do a pitch up, isn’t it?

or do I have to do a level calibration to fix this?

Thank you.

I’m not a plane guy, but AFAIK a constant up pitch is not a good thing and indicates leveling or CG issue.