1999 Chevy C3500 454 starting issue.

[evm]

My C3500 starts fine in the morning.  I drive the truck to a location and shut it off.  When I come back to start the truck again, it's very hard to start, taking about 5-10 minutes of cranking the engine over to get it to start.  It sounds like it wants to start at some points but it just fizzles out, then all of the sudden the truck just starts.  For the rest of the day the truck doesn't give me any issues at all, the truck starts right up.  I know this is an odd scenario but Does anyone know what this problem might be?    The truck only gives me a starting issue on the second time it's started during the day.