My 02 Grand Prix GT 3.8 started fine after work tonight.  It ran fine for the 1/8 mile drive to the Speedway on Steltzer.  I filled up, and when I started the car to pull away, it would not stay running.   
Anything under 1400rpms, and it would die.  I had to drive home (including 2-3 miles of bumper-to-bumper holding the idle up above 1400-1500.  Car sounded rough at all rpms.  Reminded me of a vacuum leak.   
No engine lights, no other symptoms.   
Any ideas?  I would have said bad gas, but the fuel that was sitting in the fuel rail would have still been from the previous tank, I would have thought.  Problem continued ~30 miles (and is still happening).   
Engine has 88k.  Full tune up done a couple months back.  Has K&N CAI and 160 stat.