What Causes my car to shut off while driving?

Sounds like an intermittent problem, something that takes a lot of time to chase down. Your mechanic will hook up a scanner to see what's going on inside the vehicles computer - it's called 'taking a movie' so the computer will show just what system failed & when. If the budget don't allow for a pro, then start looking for loose connections in wiring. Are you getting any codes from the computer?

On my 1992 Nissan Sentra, it would only stall on sharp right turns. I found a vacuum hose disconnected from the Air Intake manifold to IAC, and my +12 volt distribution bolt was also loose on my Positive battery Terminal. Tightened it and made 10 donut turns in the Mart parking lot and on some Freeway cloverleaf exits- problem gone! Also, Nissan distributors have a rubber gasket, just below the distributor cap/rotor, that disintegrates with age. The rubber filings fell all over the Cam Shaft sensor code wheel and caused my car not to start and stall. Buy a new distributor!

so far i have change the spark plug