my mt keeps stalling, starts, and idle's ok, but give some revs, and it will stall, is it to rich , i have put low end needle to factory setting 6.5 turns, i have 2 mta4, the other one runs fine, with same setting, can engines have slight differences?

forgot to ask is a very hard to start nitro engines in winter?, i have to use hair dryer to heat both engines up, for 1min before they will start?

thanks

dave