Sounds like the idle air bypass is sticking shut sometimes on cold start. Try gently tapping on it when the car is acting up. to see what it can act like when the idle air control is stuck shut you can disconnect the wiring plug on the idle air control valve on a cold start when it is acting normal and see if that makes it act the same as when it is acting up. The idle air control may be able to be cleaned (clean athe throttle body at the same time). If it is sticking and cleaning doesn't help, it will probably need to be replaced.
Just reading the codes will not help if there are no codes set. If the CEL has not been on, there are probably no codes.
