Have you thoroughly read through the instructions? I thought they were rubbish at first but take time to read through them and youll understand it better. it says in the running in instructions on the second page about 8 lines down. it says something along the lines of " during breaking in, yoy will experience engine malfunction problems with your engine such as stalling and bogging down". patience is the essence my friend. It happened to me but if your pulling back in a fast movement with the throttle controller on your transmitter then the engine will stall. you need to do it slowly, no jerking on the throttle controller.
oh and this topic should be under general nitro