let me know if the vehicle has been checked for trouble codes. If you have access to a scanner with live data let me know too. I just picked up a good one from launch for 35$, there is a bunch out there for around 50$. I would start with checking and cleaning the IAC and the throttle body bore. I use a soft pipe brush and throttle spray cleaner. Next I would check and clean the EGR, they can stick open a cause a vacuum leak. I would clean the MAF(mass air flow) sensor too, it combines the IAT(intake air temp) , if it is contaminated it could cause running issues like this.
I would like to see what the coolant temp sensor is reading. let me know what has been done as far as a tune or maintenance.
important to get the injector poppets cleaned, fuel injection service.
let me know if there are any trouble codes. Many parts stores will scan for free
lets start here