gas dryer would fire, but shut down before getting warm enough to dry clothes

Removed lower front cover of dryer, located coils, removed old coils by disconnecting the wires and removing the hold down bracket screws. Pulled the old coils out replaced them with the new coils by aligning the index pins on the coils with the holes in the bracket then reattached the bracket and plugged the wires into the new coils. Then closed the cover on the front of the dryer. Dryer now ignites and stays on to heat up and dry clothes.