runs about 20 seconds

[eticket]

I need some help here. My 351w runs for about 20-30 seconds than dies, and will not restart for about 5 minutes. Then it will fire and run for again for 20-30 seconds. The car was running fine about 3 weeks ago and it sat for awhile and when I went to fire it up it is running like this. During the 3 weeks span I had replaced the Edlebrock with a demon carb. So far I have rebuilt the demon carb, swapped the demon back with the edlebrock, tried a different coil, and put on a new cap and rotor. I have noticed that when I had a plug at the end of a wire that I was getting good spark until about 20 seconds and the plug was not fireing, but the engine was running a bit but really rough, and then died. I have a ford electronic distributor, I don't know if the ignitor may be bad in the stock ford electronic distributor. If you all think it may be the ignitor, what years were the electronic distributors first put in Fords as it has a small cap, not the large style caps on the 86 and up mustangs. I have a Mallory distributor I want to put in, but I would rather get it running now and then swap out the distributor, instead of playing with to many variables.
I have checked the carb and before and after and right after the engine dies I have gas squirting out the nozzles, and my pressure is 6 psi. Thanks for the help
Mike