What drhula said,

Been around coil problems for a LONG time! Fine when they are cold, but when they are bad ones, they will let you get down the road away from the house, heat up and break down, and so do you.

When I bought my Blazer, fist thing I did was give it a fresh set of plugs, new wires, and a new coil. The coil that was in it is still in the glove box 20 yrs later. But I know it was good and will help me out if the 20 yr old craps out. Check on it.