I had the same problem with my Mgt...my problem was with the radio glitching,I changed the servos and it still glitched...I can see the servos twitching. I replaced the motor with a XTM 457 and been problem free ever since...some how the stock engine was causing interference. your problem could be a possilble air leak. You said it is -8 degrees outside..so the engine might not overheat because its so cold out. Check the minor stuff first. Check the fuel and pressure line for holes or tears and then the o-ring on the tank lid for a tight seal. What radio are you using?