My 2000 Tahoe, 5.3 motor will crank over for about 5 - 10 seconds before starting up and when it does its a little rough, but idles fine and runs good, if i start it back up it starts right away no problem, i changed the fuel filter and it made no differance, i checked the fuel pressure it seemed to be fine at start up and at running 57 - 60 psi, anyone have ideas as to what i can check next or does it sound as if my fuel pressure is leaking down ? if so what causes this?
Thanks

 

Sounds like the fuel pump is going bad. Not the cheapest of fixes either. Hope I'm wrong.

 

A tiny piece of dirt can lodge in the fuel injector and cause the needle-valve to not fully seat (close) when the ignition is turned off, the fuel will then drip into the effected cylinder until all pressure in the system is neutralized.

When you attempt to restart the engine you will have two problems that cause a slow-start condition, the first is the inability of the fuel pump to provide enough pressure on the initial cycle when the key is turned to RUN and START, the second problem is the flooded cylinder.

Normally when the engine does light off it may take a second or two before it runs smooth while the excess fuel is expended and the pressure builds in the rail.
The #7 injector is the most prone to be the culprit.