Engine Misfire after 1-2 hours of operation in chilly weather.

[pinehole]

Alright guys. Here is a real head scratcher.

Symptoms. Started around September October last year when the weather got colder.
Engine would start to shake, idle would drop, misfire could be heard from the exhaust.
After running for maybe and hour ish or more, the misfire would begin.
Once after 2 hours of operation, after parking for a min and trying to start again, the engine would rotate but would be hard to start.
With enough throttle mashing it would rev up.
One time the engine turned off completely while I was stopped at a stop sign.
but.. if I turned the car off, opened the hood, let it cool off. starts right up in 10 minutes like nothing happened.

Possible causes would be with the Fuel, spark, and Air.

so. I went ahead and changed the plugs, very tedious process. and changed the air filter. cleared the codes, but the misfire still persists.
I don't drive that hard or long anymore (it would be for 3 hour delivery shifts) so not a problem but still.

The next possible cause could be the ignition coils. Even on Rockauto, its not something I want to buy 4 of only to find out that wasn't the case.

Is there a way to check the ignition coils while the manifold is off?

I thought of swapping the ignition coils on the cylinders with each other, but it wont give me a definitive solution. Plus the whole removal of the intake is not something I want to do more than once.

Anyone had a similar issue, have any tips on diagnosing the misfire when its not the air or plugs.

Again, symptoms begin at temperatures under 15 degrees C, after 1 or 2 hours of operation, and cease when I shut the engine off, open the hood and let it cool off.

Thanks.