I have an 85 3/4T Suburban with a 350 and about every 3 or 4 years I find myself changing the ignition module in the distributor. The first time it went out I was pulling a hill and I didn't think it would make it over the top. Took it to the dealer the next morning and because it cooled down overnight, it ran like a champ. They changed the module on a hunch and it ran great for a couple years until one day it didn't have the power to pull itself from a wet paper bag. Changed the module and off and running again. I've seen them act up when hot or just fail entirely. I carry a spare in the glove box with a phillips screw driver and a 1/4" nut driver. Depending on the vintage of your distributor, this could be an issue for you too.
