2003 4.8 Z71 P0300 DTC
I have a 2003 silverado. Starts up fine and idles fine when cold. Once it warms up, it starts idling rough. I've tried unplugging COP'* one at a time while rough idling and found that I can unplug all 4 coils (1,3,5,7) at the same time and idle will not change. If i unplug only one coil (2,4,6, or 8 ) it significantly affects the engine. All 8 coils have spark even during rough idle. When it rough idles, i get a raw fuel smell from the tail pipe.
If i get on an open highway/freeway, it will not act up so long as I'm moving. If i, for example, hit stop-n-go traffic, it starts sputtering, sometimes making a "clunk" sound when I take off.. almost sounds like the drive shaft fell off. But, once I get going, after a little hesitating, it just takes off and the misfire stops. Until I again come to a stop.