I'm going with fuel pump.
My car used to do this too. It would run great when it was cool outside, or the car was cool, once that pump started warming up, it would shit out everytime. I'd let the car sit for a while, it would start up and run for a few then die back out.

If you have access to one, throw a fuel pressure gauge on your filter and see what kind or pressure your getting.

One other thing I was thinking was bad timing. When the car is cold the timing is a little advanced then when it warms up, keeps the idle higher to warm the car up. Check this too maybe your off a tooth on your timing belt, unless you haven't fucked with the timing.
G/L

-Ben