Intermittent rough idle/no start

After being warm, car would not start. Acted like it was flooded. Held down the throttle, it sputtered to life and started running.
It happened again and thought since it was hot outside, the igniter was going... so I replaced it.
Test drive, all okay...
Next time, hard start again...
Rough idle...
I removed the vacuum line to the fuel regulator and it runs great! Which is weird because a vacuum leak usually makes an engine run rough?

Do I have a bad fuel regulator?

Thanks!