is there even such thing as OBD-3???? not that ever heard

they answered all the questions already... the thing i can think od is if you have the z6 head and block but the Y8 dizzy that may be why you car stalls out the dizzy are 10* degrees different in stock settings.... make sure timing is correct no teeth are jumped
you may need a cam gear,,,, but swapping the heas like the first reply said would be the easyiest and best thing for you to less time but alittle money on a head gasket...