Truck won't start in the morning

I have a '97 Chevy C/K pickup. If it sits overnight for more than 8 hours and there is any condensation then it’s nearly impossible to get it started. If the air is really dry, or if I leave it until the sun has been shining on the hood for an hour, then it starts right up.

I replaced the wires and distributer cap 6 months ago, so this doesn’t seem like it should be the problem. I’ve been getting up at 4:30 every morning to start it up, just to make sure I can get to work each day…any suggestions?