Hi !
As i'm french and don't speak very well english i tried to understand your problem and i can suggest you to look around the welds in RCM. (if it's not already done)

I had a problem on mine, in low speed the engine stalled and doesn't want to start immediately.

Here you can see where to find those welds and just have to re-welds them.
Since it never happened.

A video for more details :
http://www.youtube.com/watch?v=ZCe9EmthlAE#t=44]Boitier



3 welds that cause the problem to me (don't hesitate to re-welds others too)



I hope it will help you ..