i doubt he needs to adjust his idle although it can be a temp fix. my guess would be a TPS (throttle position sensor) or ISC are you throughing codes ??? does the car idle @650-900 most of the time ??? or does it idle low??? 650 or lower??"?
easy fix I had the same problem I would ride the clutch to a stop light or just when I push down the clutch and the RPM drops to idle the cars RPM would drop to about 200-300 rpm if I let it sit for a bit it would come back up a bit to about 500.
the fix is get an old rag and some brake cleaner find the throttle body witch is located under the intake manifold. pull off the air intake enough so that you can see the butterfly valve. then simply open the valve. you’ll have to hold it open because its spring loaded. Then spray your bake cleaner on a section of the rag and wipe up the inside of the throttle body tube the bottom of the butterfly valve and just clean it up get all the dirt and built up carbon out of there. Then put it all back together and try it again you’ll notice a biiiiig improvement. This took me about 30 mins
What’s happening is that when your car sits at idle there is a very very small gap between the edges of the butterfly valve and the sides of the throttle body. if enough dirt and carbon builds up there it blocks the flow of air to the engine thus choking it and the car stalls. If you don’t want to do this right away the other simple fix is to heel toe if you have a manual. That opens the valve up when your braking.
This sounds like it could be the iac Idle air control valve it’s an electronic actuator that lets air by pass the closed throttle body and adjust idle depending on engine load ect. These get gummed up over time and require cleaning.