Something floating in the tank that plugs ups the fuel line- That is a good thought; I can see that happening pretty easily...

If that is not the problem though, have you tried different (brand new) fuel or a different glow plug? I have seen engine problems caused by trying to use old fuel. Or even the brand or type of fuel. Some engines are fussy about the percent of nitro or the type of oil in the fuel. And some engines work better with certain brands or types of glowplugs too. I once had an engine that wouldn't run worth a darn until I put a K&B idle-bar plug in it. Pretty much all I use now are the OS #8 for 2-strokes and the type F for 4-strokes. Might take a bit of experimentation to find what works. Good luck!