New Stihl BG-86 leaf blower hiccups/dies when going WOT

I have a new Stihl BG-86 leaf blower that has had roughly 2 tanks of gas through it. I'm using 50:1 like the manual has said.

It cranks no problem, idles no problem, but when going WOT the motor wants to die. Bringing the throttle up slowly, it will run WOT no problem. i don't run it WOT for only short bursts 10 seconds or so. But it has no problems if you bring it up slowly running WOT.

Is it just because it hasn't broken in?