Dryer running but heat only stays on for short while

hello everyone,
Got my self a little problem with the dryer and need some advice.
My whirlpool dryer runs but the heat only stays on for about 5-10 minutes then no more heat (dryer still running). I have to turn my dial to off then on again (reset)for it to work again then same thing happens again and again. I have checked the ducts and everything seems clean and plenty of air flow. Im thinking it might be the gas valve coils or the thermostat.
Any suggestions? thanks