multiple misfire code
 

well i have a 2001 chevy 1500 i put a 98 ls1 in with ls6 heads and a ls3 cam out of 2010 camaro and at 2500 rpm and up it keeps throwing a random multiple misfire cod #p0300 just wondering if enyone has had this broblem thanks

Yes, I had the same problem with an 05 vortec 5.3 motor. found lots of stuff that could cause it, from o2 sensors to dirty throttle body. turned out to be the valves were worn and not seating properly and pressure was bleeding between two cylinders...