Something is wrong with my BURNER (i think it's the burner)

hello everyone, long time listener first time caller... I need some big help with what to do with my furnace.. Umm... when i turn it on, it starts right up... I have two burner thingies and they both get a good flame going... but then after a couple minutes the flames go out but the furnace/fan still runs blowin out cold/normal air.

(not air/water in there cause i had that prob b4 and the flame would go out in 1 second, so i'm pretty sure it's not that ) 

I don't have the money to even get a diagnostics check on it.. i'm poor/laid-off.. but some people on the phone said maybe the heat exchanger (god i hope not) or someone said that a heater sensor thingie could make the flame go out.. or maybe get a new themo-stat... Any help would be great, my wife is freezin and if i can get this fixed i'll get big points... ya know :)  oh yea

u can even email me if u like

<a href="mailto:bettyandme2@yahoo.com">bettyandme2@yahoo.com</a>