how is the compression?? sounds like your running too lean, richen high and low end an 1/8th. Nitro engines dont idle for too long since they will load up on fuel and stall(flood). Do you need to raise your idle a little bit? Maybe your low end needle is set wrong. it should be set so that when you pinch the fuel line it should idle for a couple of seconds then raise a little and die. if it runs for a while then dies out your low end is rich, if idle raises quickly and dies your low end is too lean. hope this helps.