I have a 2013 Toyota Corolla Ascent Sport, whenever the car is driving normally the engine will not misfire and runs smooth, however if it sits too long and it heats up cylinder 4 starts to misfire.
Currently I've tried swapping the cylinder 2 and cylinder 4 coil packs and replacing the cylinder 4 spark plug to no avail. Whenever the engine heats up the misfire comes right back to cylinder 4.
Is there anything else I can test to make sure it isn't something like a fuel injector or a bad ECM?
Ascent Sport
Have you checked over both of the turbo's?
Get a bluetooth OBDII scanner and an OBDII scanner phone app (IIRC Torque on Android is decent). This will let you log all the sensors in a CSV file while you're driving, and show you any warning/error codes it has received in the past. Hopefully the sensor data shows a difference when misfiring, giving you more info on what subsystem is playing up.
Otherwise maybe get a quote from a mechanic to at least troubleshoot the issue, though it probably won't be cheap. But they'd probably do the exactly the same as above, just with more knowledge of what to look at.
As long as you buy Torque Pro! The trial is years out of date and the paid version is well worth the upgrade.
Could be a faulty connection in wiring. Works all until it heats up.
Have you swapped injectors between cylinders?