(EDIT: multiple post, I have merged your other post with this one. )
THAT being said, are you at all familiar with tuning a glow engine?
try this for starters, as it sound most likely that the engine is tuned slightly too lean.
do this with a helper to hold the airplane!!
after the engine is started, with the helper having a firm hold on the airframe,
have him nose the airplane UP. if the engine quits immediately (or nearly so) turn the high end OUT (counter clock wise) half a turn and try again.
turning the needle valve OUT allows more fuel, making the mixture more rich.
another good idea is to turn the needle valve in all the way COUNTING how many turns it takes, so you can turn the needle valve out a specific number of turns.
one other thing that MAY be causing your issue is the 'clunk' AKA the fuel pickup line inside the fuel tank.
if that becomes clogged, or kinked forward, that will certainly cause problems.