Common problem with IAC valve when it starts going out. Intermittent issue, doesn't always throw a code into OBDII.
Find where it is remove it, spray it with carb cleaner and put it back in.
One of the idiosyncrasies with drivability problems, is usually the worst symptoms are caused by the most minor cause.
If the car is running absolutely fine and all of a sudden starts acting bad..., look for loose or disconnected connectors, failed sensors, worn, burnt or dirty solenoid/motor actuated parts.
So, some of the other things to look at in your case, are: EGR, Fuel Injectors, one or more coils, loose or dirty connection to ECM, vacuum leaks, weak battery, alternator regulator not maintaining at low rpm...
Try the IAC it's fairly simple, but basically need to run a scan tool on your setup, or you start chasing your tail.