Why do you think it's overheating? The proper way to test a dryer for proper heat is put a temp probe in the exhaust vent run the dryer on time dry hi heat with no load. watch the temp it should rise to a temp that is close to the operating thermastst rating lets say 175 degrees you record that temp while having your muti meter on each terminal of the stat so when the stat contacts are closed yuou read continuity when they open you read voltage SO while your watching the digital temp probe it gets to 175 degrees then it starts to drop the thermastst should be reading voltage then the dryer starts to cool down lets say to 113 degrees then the contacts in the stat close at that temp or whatever your dryer does you should read continuity so make a long story short you take the two temps hi and low divide by 2 so thats 175 + 113 Divide by two and a properly heating dryer will read about 145 degrees on an average. this is proper heat give or take a few degrees to dry clothes now if it doesn't cycle off untill it reaches over 200=225 degrees its cycling on the hi limit instead of the operating stat. you can tell if it is when the dryer shuts off the element and starts cooling down the hi limit will read voltage. If your dryer is cycling on the hi limit and not the operating thermastst you may have improper or restricted air flow such as a plugged vent all dryers need a 4in hole with a maximum of forty foot vent run and remembering to subtract 8 feet for every elbow in the run. if it cycles on the hi limit and the operating stat never opens or is opening late or early it needs replaced if the dryer gets too hot it will cyle on the safety stat and disable either the heat elemnt or totally kill it all together Hope I didn't confuse you to much I know I am lol its hard to explain but I hope you get the idea or what I am trying to say

Some things to look for are the drum not turning to speed a shorted to ground element,it will still heat and get real hot, a plugged or restricted vent, You saud you replaced the vent but sometimes when the dryer gets pushed back against the wall the vent gets smashed without you knowing it. a failed operating thermastat. Blower wheel not turning Overloading with to many clothes you should nave 220 volts going through heater at about 22 amps not 120 at 22 amps the centrifical switch in the motor only puts power to and power off to element check your line voltage at the cord for 220 volts where it hooks up to machine. The element is a 220 volt element not 120. tocheck the motor check continuity at the centrifical switch at the two biggest wires bmanually releasing switch it motor try that got to run