i had the same problem. it might be interesting for you to check my post out. http://www.rcuniverse.com/forum/m_4089701/tm.htm
few things that i changed to make the problem go away.
1st the fuel tubing was very loose. tank to the clunk and clunk to the carb. i think there was an air leak there.
2nd i changed the ignition battery, from an old 4.8v 1500mah to a new 6v 2300mah.
3rd i changed to pennzoil from castrol.
i don't know exactly what helped but my engine wouldn't start hot at all and it would stop mid air after about 5mins, now the engine starts hot or cold after a few flicks
hope this helps