My '05 5.4 has started running a very low idle (around 510-540 rpm), running rough at these speeds, and occasionally "stumbles" and doesn't crank.

I know that my motor is under the injector "recall"/extended warranty, as I have already replaced my #5 injector - is it likely with these symptoms that one or more of my others is acting up?

Any idea about what it costs to replace all of the injectors? If this is most likely my issue I would rather pay for it now then have my motor quit on me (again) when I'm out somewhere and have to argue with Ford about replacing all of them (they probably won't!)

Thanks!