Here are your parts
Replacement parts for WHIRLPOOL REX5634PQ0 | AppliancePartsPros.com

Here is the wiring diagram
https://www.servicematters.com/d...0Sheet%20-%208528187.pdf

After the heating element was replaced did it ever work OK?

Just to eliminate the vent as a cause try the below
Undo the dryer from the exhaust
Run a load
If the load dries correctly then you have a vent problem.
Clean/check the vent system. Make sure the outside louvers open fully.

If you do not want lint in the house.
Take a pair of pantyhose, put one leg into the other and attach this to the dryer exhaust.
Leave enough room behind the dryer so it can blow out like a windsock.
Run a load.

Both the above will allow you to check the air flow and temp.
Try different temp settings to see if it does make a difference to the exhaust temp, could be the thermostat's internal heater is on all the time.
Also the above is NOT recommended for a gas dryer due to possible carbon monoxide problems.

Does the timer advance in both timed dry and auto modes.
If it does not advance in auto modes, this may indicate a grounded element.

I would remove both wires from the heating element and check it for resistance, should be approximately 10 ohms. Then check from each connector to ground/case, should be an open (infinite ohms).

Clean the blower wheel, also check that it is properly attached to the motor's shaft. Sometimes it can strip out and rotates but does not but not at full RPM.