Why isn't my gas dryer heating up?

i have a maytag atlantis gas dryer and the problem is that it heats up for about 5 minutes or less and the after that the air runs cold and i checked the gas chamber or whatever its called and the fire is not running no more nd the redish orange thing that lighs up nd than turs off two and about a minute it turns on again then a minute later it turs off again nd stays off and the dryer is rotating nd the air is cold and the clothes a little warm from the beggining nd but isnt heating because of the fire or gas going off? what is the problem or whats wrong with it?