What the hell is going on....
If not, the IAC valve might just need cleaning or possibly you got a cylinder misfiring.
Trending Topics
The Best V8 Stories One Small Block at Time
I know you said you started it and it died at idle, but wondering if it was still at temp.
The reason I ask is mine was doing something very similar but it would run ok in open loop before it warmed up.
If you have access to a scanner, check your O2 sensors- I had a fwd one start to fail that was sensing a lean condition that wasn't there- made the car run WAY too rich and idle like crap. Quick check is to see if you are blowing black smoke at idle- best is with AC on and in drive to load it and see if it's smoking. The car SHOULD see the load and maintain a constant idle and adjust for rich/lean conditions.
A fail code may not be set or give you a SES light, look at the scanner to see what the sensors are actually reading. Based on how many miles you have on your car, it (O2 sensors) could be the culprit (along with your CATS if you still have them).
The final fix for mine was replacing the entire PCM
but my symptoms were more elaborate.... 
