admiral electric dryer heats sporadically

Dryer heats sporadically, sometimes on timed dry and others on sense dry. Sometimes it doesn’t heat at all. It’s only 1-1/2 years old. It can take 3 hours to dry one load.

I checked vents and they are clean. Same thing happens when disconnected from outside vent. All 3 thermostats have continuity. Doesn’t seem to be the blower since plenty of air is being generated. Any other suggestions? I was wondering if it could have something to do with the timer?