It is the 5cyl 3500 I mine had a miss fire code, and was idling rough too There is a service bulliten about the spings on the exhaust valve springs and it is covered to a 100,000 miles, bad thing was my truck had 130,000, it is a 05OBDII Chevrolet Code Definitions Be sure to double check the codes Anything P1000 to P1999 or P3000 to P3400 will be Manufacturer specific and may not match the ones listed here Check specific manufacturer pages on the site, as some of them, we list the OBD2 codes on those pages for those specific vehicles
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