I have a 2001 Chevy Silverado Z71 with a 5.3L v-8 that I am trying to fix. It has 70k miles on it. The truck had an intermittent P0300 random multiple misfire code that would trigger the check engine light a few times a week. The truck can be a little hard to start and smells a bit gassy at startup. I originally suspected the plugs/wires, so I bought a new set of delco wires and delco iridium plugs. As I was removing the old plugs, they were all normal with the exception of one cylinder, which was the passenger side second cylinder from the front. That plug was black and sooty. I put all new plugs and wires in and started the truck back up. After a few minutes of ldling, the P0300 code came back. I pulled the suspect plug and it was again black while the cylinder next to it was nice and normal. The coil seems to be ok on that cylinder since it sparks regularly against the exhaust manifold when testing. Is there a way to test the coil on that cylinder to get a definitive answer? I have a multimeter. At this point, I am suspecting the coil or an injector that is stuck open causing that cylinder to be very rich. Most people are telling me stuck injector based on 7 plugs being normal and one being black. These seem like great forums, so I figured I'd see what the fine people here had to say. I plan on doing a compression test just to see how that cylinder looks compared to the others. I guess it could also be EGR related. P0300 is such an ambiguous code. Thanks!