Fuel injection help

I recently installed the Edelbrock EFI system on my 71 Charger 440. The car will start right up and run for 5-10 seconds before it sputters and dies ( It dies quicker when I press the gas to try and prevent it from dying). I have constant 50lbs of pressure on the fuel rails. All the parts on the car are new, fuel pump, fuel lines, wiring ect. SOMETIMES the car will run fine for 2-3 days like nothing was ever wrong. But then The constant fire up and die problems come back a few days later.
At first I thought the gas may be the issue, so I bought a new gas tank, and put fresh gas in it, however the problem has persisted.
Items I have replaced: Ignition switch, blinker circuit, gas tank, gas, fuel pump, distributor, Valley pan, Coil, spark plugs, spark plug wires, All gauges, the motor is completely rebuilt with new edelbrock EFI system installed and timed the motor.
I've contacted the guys at Edelbrock and they were less than helpful. They suggested adding fuel to the computer, which I did, However the problem wasn't fixed. All that did was burn out the plugs. The car ran better with the fuel addition set to 0% than it did when they had me bump it all the way to 50%.
So, I reset the fuel settings to 0% across the board and it actually fires up and runs for 10 seconds before dying. I've played with the fuel and spark settings but there isn't any change. I can drive the car around town one day,with fuel settings at 0%, then come out into the garage the next day, and it fires up, runs for 10 seconds, and dies.
I'm open to Any ideas or suggestions. They would be greatly appreciated. Thanks in advance.

I am by no means an EFI expert- but I have fiddled with it some and I'm still working on my EFI setup. I have two suggestions for you: first, is the fuel pressure regulator supposed to be vacuum referenced? If it is, the computer would be expecting closer to 40 psi (or less) at idle and then you're already supplying way too much fuel to the motor. It would go up to 43-60 psi (whatever the system expects) when you get on the gas.

Second, the computer system should give you an idea of what is going on. Is the computer warming it up way too fast and making it go lean? Is the table way too rich to start when it's cold? The O2 readings and warm-up enrichment table settings should tell you where you're starting- and if that's wrong, it probably won't get very far.

If it's none of those things, sensors and wiring... EFI systems are really sensitive to noise and ground issues. Does the computer have a "live view" of the data? Does it report the correct RPM? That will mess up everything if it's wrong.

Hopefully some of the EFI experts also chime in. There are a couple- and I'm very interested to know if this system works for you or not.

So after peddling with it before I headed back to college. I started unplugging and testing every sensor; trying to start the car each time I tested a sensor ( just to make sure it wasn't a bad connection. I Unplugged the MAP sensor and I noticed the VAC reading on the calibration model changed from 25.5 to 23.2. Not a big change but the car actually acted like it wanted to run. So I removed it from the manifold again, and reinserted it into the manifold, then moved it back and forth before plugging it back in upside down, yes, upside down. connecting the wiring harness back to the sensor, jumped in the car and the VAC read 0.0. JUST like the owners manual said it is suppose to read when the system is turned on. The guys at edlebrock told me for months that the VAC number didn't matter and it was just a number that the computer puts out. I always thought the number mattered, because when the car would run, that number was NEVER over 15.2, but I didn't argue with them because they were the "professionals". Well that number FREAKEN MATTERS! The car has run ever since, and when it does cut out and die, I just have to unplug the sensor, move it around a little, plug it back in and the car will run for another week or so. I'm not sure how to test to see if the sensor itself is bad or if the wiring harness has a short in it. But the car runs ( rich I might add. Which points to the sensor itself being bad) Im just grateful and relieved I have found the issue. I'm 98% confident I have located the problem. I can finally see the light in a very long dark tunnel.

I think Edelbrock just uses GM sensors. The manual should have the part number so you could get a new one and try it?
I'm not really impressed with the Edelbrock pro-flow XT controller and software.

Sensor could be your issue.

My MAP sensor just died in my MSD Atomic EFI and my car behaved exactly as you described. The digital display pointed right to the issue. I tossed in a new sensor and all is well.

I suggest joining whatever Edelbrock forum is available. The users are quiet helpful...at least over on the Atomic EFI forum they are.