Extreme cogging with Quark 125B Airmaster + Futaba 3PK?

I've got a strange problem with my Rustler VXL. My setup is: Velineon brushless motor, Quark Airmaster 125B, Turnigy 5000mAh 3S 20C LiPo geared 28/86. And since a few days I'm using a Futaba 3PK 2.4GHz Fasst system to control it. But before I only had sometimes cogging, almost never. I was using a cheap Acoms 2.4GHz transmitter + receiver. But since I got the 3PK it can cogg for an unlimited time if I just push the trigger very slightly.

So, I've got no changes in my setup, only change is a cheapo Acoms 2.4GHz rx/tx to a very expensive Futaba 3PK 2.4GHz Fasst rx/tx. Isn't this a bit strange??? What am I'm doing wrong?