Try this:
1) Start the car. (Don't touch the gas pedal)
2) Let it die.
3) Turn the key off.
4) Start the car again. (Don't touch the gas pedal)
5) Let it die again.
6) Turn the key again to start the car. (Again, Don't touch the gas pedal)
It should now remain running without touching the gas pedal as you've let the computer re-learn how to control the idle.
If that does not work, look around for a vacuum hose that may have come disconnected somewhere on the engine and is sucking air.
DON'T start throwing a bunch of new parts at it trying to get it to run right. It's a waste of money replacing parts that weren't bad to begin with!!!
