1998 chevy 5.7 starting problem

1998 Chevy 1/2 on 4x4 w 5.7. new GM crate motor last year. New starter, battery, alternator. doesn't like to start 1st thing in the morning. doesn't matter the
outside temp. 90 or 40, same problem. Fuel pump tests OK, fuel pressure reg tests ok. New fuel filter. New plugs, new wires, new AF. engine cranks like a happy bastard but won't start. 10-15 tries cranking for up to 20 seconds each time. Smells like its flooded, but how can it be? Eventually it starts and then runs fine and will start without issue the rest of the day. Throws no codes. Only thing I have left that I can think of is fuel injectors, but if the injectors were bad it would throw a code, right? Any ideas on things to look at before resigning myself to taking it into the dealer for a $500 reaming?
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Check the FP regulator again.
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Is this a recent problem or has it been doing this since the engine swap?

How many PSI exactly?

Brand of spark plugs? How about the distributor cap and rotor, age and brand?

Not necessarily, but there would be clues in the data stream.

Low fuel pressure. Fuel draining back to tank after long set. Fuel pump relay not working. AC Delco spark plugs only, AC Delco cap and rotor only. Leaking fuel pressure regulator. Stuck injectors. Plugged exhaust. Low battery voltage while cranking.
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Same problem here. Especially bad after it sets a few days. How do you prevent fuel from draining back to tank?
Thanks
Ozark
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