Kitchen Large Electric Appliances - Whirlpool Gold Dryer Turns Off After 2 Loads

I have a Whirlpool Gold, Ultimate Care II, Heavy Duty Super Capacity Plus Dryer (can't find a model #). Its about 7 years old. Sometimes my dryer works fine for a couple of loads and then turns off before the timer expires on a third load. It will not start until I let it sit for about an hour or more. I presume it needs to cool down before it will restart. Once it does restart it sounds like its straining to start. After it sits for a long time (overnight) it starts and sounds fine. I opened it up and cleaned it really well, getting all of the built up lint out and everything looks good. The drum rotates by hand easily and I don't see any obvious signs of overheating. Is there some sort of over temp breaker within the dryer that may be tripping prematurely? Any other ideas? Thanks.

i dont know about prematurely all dryers have at least one over temp switchs some have two. if this is triping there seems to be a blocked air flow some place i have never seen one that is weak
either good or bad check vents to make sure no lint build up (start with the cheap fix first) if all clear check the wiring diag to see where high temp switch is located and replace. have seen a lot of house fires last winter from lint build up clean real good