Stalling Terios


Hi new to this site. I have a 2001 Terios, automatic rear wheel drive. Every now and then it stalls for a fraction of a second and the MIL light comes on. The engine then carries on as normal. Once it has stalled completely the car coming to a stop but restarted no problems. My mechanic had a look at it and found nothing wrong. He did manage to get the error codes being 71 and 83. Any ideas what is the problem or what the error codes mean?

Cheers Terry