If it is turning at the right speed and you knwo for a fact that yoru battery is in good shape, my first guess would be a fuel pressure issue. The chevy trucks were known to have fairly predictable fuel pump problems. I have seen the pumps get "weak" either int eh fact that the motors current draw goes up or to the point that the impellers is worn, crack, or broken to the point the flow is down.
A quick way to verify my guess would be to cycle the key 3 or 4 times before yous tart it. Jsut turn the key to the on position until you hear the pump come on to prime the system. then turn the key off and on again. Repeat 3 or 4 times. Then if hte truck starts normally without the hesitation, you have a fuel problem. If not, keep lookin!
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