I have a 2000 Silverado with a 5.3 vortec and over 200,000 miles on it.
It started having trouble starting about a year ago. It crank a few times before starting. Over the past year it increasingly got worse to the point now where it takes a long time of cranking to start. Once it is running it runs very rough almost to the point of stalling. but once you are moving, and going down the road there seems to be little or no problem. It starts best if it has been sitting for say overnight. I took it to an auto parts store in town, and the code they came up with was a random cylinder misfire. I changed the plugs, no help. I changed the fuel filter, no help. I changed the plug wires, no help. I have removed the coil packs individually, and no noticeable difference.
I have heard that the problem maybe related to the catalayic converter. I don't have clue what to do next. Could someone please help me to find a fix the problem.
Thanks Bobby