03 GMC Sierra starting problems

[badriand]

Been going on for over a year just can't track it down. My truck sometime will choose not to start after turning the key forward, it doesn't make any sound what so ever no clicking nothing. It has full power (not a battery problem), sometimes i can leave the key forward and let it sit a minute the try it and it cranks right up. At other times that doesn't work and i have to take the key out and back in and it cranks up. I have replaced the neutral safety switch and check fuses etc. I never really know when it is going to do it. Seems not to do it as much when it is cold outside but does it more when warmer temps. I don't have any codes or security lights on either. I just hate to keep buying parts and not be the problem. any help would be appreciated. thx