Dryer Not Drying Correctly

Our dryer just suddenly stopped drying correctly.We cleaned out the vent line and there is nothing to obstruct the airflow.It starts out with heat and then the heat is very very low and it takes forever for the clothes to dry.I was thinking to order a few parts to replace and hope that one of them solves the problem.I was going to order the Thermostat,Thermal Fuse and Sensor and hope that one of them solves the problem.I was going to replace the Thermostat first and see what happens from there.If you have a better way of going I would appreciate any help that would make things easier.I appreciate your time and help.Thank You and Happy New Year.