I honestly have no idea if this is something you can diagnose/fix but basically as the title says, sometimes my car likes to run smooth. To my memory the few times its happend the sun was out.
The only time it was not sunny. (the sun was out earlier that day), i let the car warm up then drove for about 10 mins until i started leaking coolant because the rad cap wasn't fully on after i fixed that issue it was back to running rough when i started it. (Turned it off to let it cool down)
The other notable occurrence was the first time it happend. I drove to work around 10 am then drove home at 2:30 ish the sun was also out and thats when i first noticed it

Changes when running better
-Quiter/cleaner exhaust
-alot less vibration
Very little to no vibrations
(There is a noticeable change when turning the ac on and off)
-smoother shifts
(It feels like i cant actually drive the car when its like this)
-smoother stop/go

"Rough" running
-lots of vibration
Note: po installed soild motor mounts
I can visually see parts shaking, main example: steering wheel, headlights, hood latch (see vid below)-loud (i have a cat, resi, and muffler)
-lots of bucking (letting off throttle, starting from a stop)
-runs rough all around (rev suddenly drops as opposed to progressively returning to idle. Turning of the car is a sudden cut off)

I wrote this at 4 am so i apologize if anything doesn't make sense or is spelled wrong.
I appreciate any input/help!