Whirlpool WGD4800XQ1 gas dryer not staying hot

[Davidmarybrown]

The heat will not stay on, will work fine for most of the first load for they day but after that the heat goes on and off when it pleases. Had a repair man out and it cycled fine for him for about 30 minutes one and off as expected with and without a load. 2, 3 minutes without load 5, 6 with load. I have disconnected the duct, replaced the high/low temp thermostat, pulled unit apart and cleaned every part free of lint. Replaced coil. All wiring looks fine nothing burnt or pinched. When the pilot heating element comes on it fires fine, I have not see the element come on and the gas not ignite so I do not thing failing pilot element. Dont want to pay another tech not to fix it and hate to buy new if it's a $50 part.