My Expedition is stalling at stop signs and is idialing rough.

What is your question?

I have been experiancing this for a couple times now when i get to a stop the truck stalls out and i place in nuturl it starts right back up. or somtimes i get there and it idals at a low RPM below 500 and then stalls out. i have changed the Air Filter, Fuel filter, and throttle Position sensor. i have been reading that it might be the O2 sensor that might be causing the stall. please advise before i have to pay a hefty repair.