Running rough, and revs up & down?

I have a 91' 5.0 mustang, and when I left the house this morning it drove fine for about the first 5-10 minutes, but then it started missing/sputtering out of nowhere? And now when I come to a stop, or if it is just idling, it will idle up and down over and over from about 800 rpms to 1200 rpms?

So I checked for vacuum leaks, cleaned the MAF & throttle body, and put a new IAC (idle air control valve sensor) on it. It now doesnt feel like its missing/sputtering as bad, but it still revs up and down over and over while idling?

Anyone got any suggestions on where to start next? I was thinking maybe the TPS (throttle position sensor)?

Any feedback is appreciated.

Jason

Just for the hell of it, I went and unplugged my MAF sensor, and the car will now start up, but then just dies? Connect the MAF back up, and it will just sit, and idle up, and down over, and over? It will run/drive "ok", but at stops/idle it just idles up, and down? Does this mean my MAF is good or bad?

Any other suggestions?

Ended up being the EGR Valve...