'01 Ford Mustang GT Intermittent Starting Issue

Car has 30,000 mi. 4.6L

Battery went dead when car wasn't started for a while. Tried jump starting it, but the engine just turned over wiithout firing.

Charged the battery, and engine still turned without firing. I read something about having to turn the key off and on several times to get fuel to the engine (in case the lines were dry). Tried that and at one point the engine fired.

It ran well until it started to warm up and the idle was lowered. At this point it was a little rough, but not bad. After 15 minutes or so, I turned it off. I immediately tried to restart and it was back at turning over without firing. Packed things up for the day.

Some weeks later (nothing was done in between) I got it to start again, this time it died on it's own after 15 min.

I have checked the valve on the fuel rail and it never has any pressure, although I didn't check it after I shut the car down voluntarily. I disconnected the other rail without the valve, and there was some fuel, but not much and no pressure.

I haven't yet checked for spark yet, but it seems that fuel is the problem.

Any suggestions would be appreciated