Ignition and Stuttering issues 92 Silverado 4.7L

92 Silverado 4.7L. Engine has started stuttering and getting worse and I am not sure where to start to fix it. I am sure it could be something simpple like a bad plug or injector, but I need to find out where to start first. Second, when I try to turn the key to start the truck, It doesn't always start, Sometimes I need to turn the key a lot of times before it starts. It doesn't crank but does click. The light on the dash come on but doesn't always start. Thanks