2002 Ford Escape 3.0 V6 - idle is not steady

My 2002 3.0 V6 Ford Escape's idle can be sporadic, going up and down, sometimes almost dying and sometimes jolting me forward in traffic (when in D).

I can recall only one time where it actually died in traffic, months ago, but it started back up immediately. And it hasn't died since, however it has come close, and I have revved the engine to keep the revs up

When driving at any speed at all, it drives perfectly smooth. What could this be?