My car starts but shuts off after a few seconds of running and I dnt know if it needs a new fuel filter or fuel pump?

What is your question?

I just bought the car and was told it needs a major tune up because it has been sitting for about six months without being started but I have been driving it for three weeks and it runs smoothly until today when it just shut off on me in traffic like I said it will start back up without any problems it just doesn't stay running for more than a few seconds