Heat will turn on when first start and then turn off. Checked with ohm meter, radiant heat sensor, thermistor, thermostat, high limit thermostat, gas valve coils and the igniter... and all seam to be per spec
Any thoughts?

Hi Scutr and welcome, check and clean the vent duct, sounds like your dryer is getting to hot.

All driers will do that when the lint builds up like concrete on the inside of the air ducts and the grease gets dried out in the bearings. You need to totally tear it down and scrape out and wash all of the parts except the motor, which you vacuum out unless you want to do some really expensive repairs later. Halfway doing it will not work. This includes the exhaust vent, all the way, even the outlet on the side of the house, if you have one. You can go to YouTube to see videos on how to take it apart, but do a very good job or it will fail again quickly. I would get a new belt and change it while you have it apart and get some white lithium grease and grease all bearings you find. You need to pull the support rollers apart to grease the pins with white lithium grease. You need to clean out a drier every year, at least, according to the manual. All sensors work together by comparing temperature, so all need to be cleaned. You just unplug the wires from the sensors and remove ductwork that they are attached on (Label wires!) and clean the entire thing with soap and water. Make sure you go all through the dryer and get all parts like the blower fan and housing, vacuum out motor well and clean exhaust. Mark all wires you unplug so you know where they go. This is an easier job than you would think. You need a meter to test any fuses/safeties that may be blown, there is more than one safety, so check all of them along with the thermostats. One may be out. The NTC sensors should be at the intake and at the exhaust air ducts. You will see them on the schematic diagram.
See: http://www.youtube.com/watch?v=A6wmD502-xE and: http://www.youtube.com/watch?v=OBNDbyRm68M&feature=fvsr
http://www.youtube.com/watch?v=a73HTFkcB90&feature=relmfu
You did not say what kind of dryer you have , so I cannot send a manual. A number means nothing; it could go to a John Deere tractor for all I know.