Heating issues with our Neptune MDG4000bww

[NeedingHelp]

Greetings,
  Was looking for some help for my parents dryer issue.  They have the Neptune model MDG400bww and it isn't drying the clothes and has been puttin out the smell of gas.  We thought there may have been a clog somewhere but have found nothing (Had the local gas co come out to make sure it wasn't something on there end and it wasn't).  While front end was off and we could see if it was igniting, we watched the igniter light up, produce a flame with the gas, then the igniter would shut down and as soon as it would cool the flame would quit all in a matter of 30 seconds. Not sure if this is normal or what.  Looked at http://appliancejunk.com/forums/index.php?topic=6205.msg27034#msg27034 and this particular topic said it was prob the heating coils.  In ending, hoping someone can help us out so we don't have to spend money we don't have to have it fixed or buy parts we don't really need. Or blow up the house.  Appreciate any help or feedback.
-MB

[jumptrout51]

Check for a blocked exhaust vent.

[JWWebster]

If it works some but then quits for a while then the fuse, the igniter, the flame sensor are all fine, (with the exception of the flame sensor which may be sticking with age but highly unlikely), the only other thing in the circuit is the coils which do get weak and fail when hot. These are cheapest to replace. If after replacing these and the problen is not resolved then you have a control issue,(still this is highly unlikely but does happen). As Jumpy said clear all air restrictions before changing any components.