Does it shut down instantly?
Can you keep it running with the brake on while you give it gas?
I would start by having him remove the air intake hose to the engine and clean the throttle body bore out real good with some carb spray. If it still acts up, replace the idle air control valve.
Remove the hose clamp securing it to the throttle body. Once removed look inside the hole,,,that's the bore,,,,clean real good. The idle air control valve is circled.
Click on image below.
It will need to go on a diagnostic machine and a scan tool to see how all the sensors are working. One last thing that comes to mind is the mass airflow sensor, they were very common to fail. It's shown in the diagram i sent.
Best of luck my friend!
Thanks for asking!