My 2004 Colorado 4 cylinder has been plagued with similar issues. When the truck was in New Mexico for a number of years, it would only happen if I had not driven it for a while (months), and then drove a short trip. So my thought was moisture. I drove the truck back east, and it has happened more frequently. Like Carmen above, it happens in groups. So maybe a dozen times this summer. The common threads are:
1) If you let it sit for 15 minutes, it starts normally - no blue smoke, no gas smell, no roughness, and no delay - Just like when the condition is not happening - Turn the key, one revolution, and it starts.
2) It typically happens when you start normally, go for a 3 to 10 mile journey, shut it off, then try to restart after 10-15 minutes. If I go farther, then all is well. If I try to start it when the condition is happening, the thing just spins over without ever a sputter. If I wait 10 minutes, it just spins over without a sputter. If I wait 15 minutes - it starts on the first revolution - no smoke, no gas smell, no rough running.
3) It seems to happen the same whether it is raining or dry and sun shining.
4) the weather has turned a little cooler, so I have not seen it for a couple of weeks.
5) I read somewhere that you should wait for 5 or 10 seconds with the key on before starting. I tried it a number of times - no effect.
My mechanic has searched his database of weird things, and nothing. My guess is that it is starved of gas since there is no smell or rough idle. I am also guessing that it is not just a pump issue, since when it starts - it is immediate. Maybe a temperature sensitive computer control on the injectors???