car starts, runs about 6 minutes, check engine light comes on and engine dies. cranks, but won't start for about 30 minutes. just changed coolant temp sensor, still doing same thing. Could it possibly be the Catalytic converter or the ECM?
I honestly would replace your Exhaust gas recirculating valve(EGR) valve, or idle idle speed control (ISC). This is a less costly repair than a catalytic converter replacement, if you are not sure of the origin of concern.