New engine wont restart

Replaced the engine in a 2000 ranger 3.0 flex fuel. The engine started immediately. I let it run for about 15 minutes until the gauge read a normal operating temp. I then shut it down to finish tightening the exhaust bolts. Now it wont start. I have switched out the coil, installed new plugs prior to installing the engine, have fuel to the rail, have spark, ensured all connectors and the ground are secure, and have a new fuel filter. I bled the air out of the fuel system at the valve on the rail. The engine turns over great, just wont start. Also checked fuses. What else can I check? This is a used engine with 40K miles.

48 lbs fuel pressure with key on. However it falls off very quickly.58 lbs when engine is cranking. Neighbor added a few drops of fuel to intake and the engine tried to fire. Seems like fuel problem to me too. There is 13 volts at the injectors.

The kid at the parts store said that the valves got fried since we ran it without the pipes tight. Seems like a stretch to me.

This is making me nuts. Thanks for the help!