I can help with your car; if an older model pre-1985 it sounds like you are getting moisture in the distributor cap. Make sure to write down the proper firing order on cap and corresponding soft plugs, remove cap, wipe down and store in a warm dry place. Replace on a day with little humidity with a small amount of silicon around the seal. It should fire up with a fully charged battery, no problem. If a later model GM (after 1996) this is a common problem with the positive posts. I keep some battery terminal cleaner and a 10mm socket wrench in the car just in case. Wipe the posts with the cleaner, and it will fire up. All repairs should cost less than $10. Hope this helps and best of luck.