Sounds like you need a new glowplug; go to the nearest HobbytownUSA and pick up a few.
Coldplugs are for warmer weather and medium/hot plugs are for colder weather you might want pick up a fuel filter also and see if they have any books on RC Basics believe me from experience it will help you out a lot.
Do yourself a favor and read your manual for the break in process completely; do not forget to do this and if you want your engine to last make sure you put your piston down at bottom dead center (BDC) check this video out.

http://www.youtube.com/watch?v=v9uPLys90gQ


From what I heard and experienced the life of a nitro depends on how you break in thew engine and how you take care of it.
This is a pretty good book; it helped me out a lot.

https://secure.rcstore.com/pcd/eServ...lTdWJUZXJtPTA=