2002 Sierra problem

[Dick Dale]

Everytime it rains, the engine won't start. It will crank and crank but no spark. Last week, it started cutting out on the road for me after it rained the night before. It will even chug a little when its been sitting and is real humid out. I have gone through 3 dist. caps and I know it needs a tune up, but this is damn ridiculous. Its a 4.3 with 100,000 so I was going to go the plugs, wires, cap and rotor anyways, but I want to FIX it, not band-aid. Any clue? I was told the dist. cap was cracked once and that condensate was building up but how the heck do I fix this for good. I'm commutting an hour and a half each day in my Old Mans 454 SS so I need help before I loose all my money on gas.