I have hit a road block with my 5.3 swap

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I have done a dozen of these swaps and never had this problem or many problems to speak of. This one is in a 70 C10 short bed. The motor has been in and running for over a month. I have driven it around the parking lot at my shop and moved it around the shop a dozen or more times while continuing the build. Last week got the truck out drove around a little and did a few donuts then pulled it back in the shop. Everything was fine an this point. Few days later, start the truck up to move it and its running rough, like a misfire. Checked fuel pressure at this point and everything was at 58 like normal. This week, go to fire it up and nothing, i mean nothing. It will prime the fuel pump, hold pressure and just spin over. Today I hooked it up to the lap top and no DTC's are recorded. Pulled spark plugs and they are firing, pulled the fuel rails, and they are pulsing and have a good fan of spray. It is wired using the stock fuse block like I have done all my others. I have had one die on me before that ended up being the fuse block but it wouldn't do anything, not even prime the fuel pump. Any thoughts would be appreciated.