97 C1500 won't start after sitting long

Here's the lowdown. I have a 97 C1500 4.3L with 212K. For about a year it's been hard starting on damp mornings until recently it won't start at all. If I jump it with another vehicle it starts eventually and when it runs, it idles fine, runs/drives fine and starts up fine. But when I let it sit for more than 6 hours it won't start.
Here's what I've done so far....
New plugs, new cap and rotor, new fuel filter, ignition coil checks good, fuel pressure checks good, battery connections are good. The spark is not blue but is orange, which is not good. I'd appreciate any suggestions.
Also I'm wondering how the stop light switch connects back onto the brake pedal with that "clippy" looking thing.
Thanks
Emily

Well, I had to figure this one out on my own. I did a fuel leak down test and lost 10 PSI in the first 5 minutes. I put a new Delphi pump in (not the cheapo Airtec). Started right up on the first try. Haven't had any starting problems since. I hope this can help someone.