I have a 2007 GMC Sierra "New body style" 5.3 and I have a misfire on cylinder 8, I have changed the spark plug, plug wire, coil and finally the injector. I have done an injector flush but still a misfire on number 8, anyone have any other tips or ideas as to why this is having a misfire?

 

stock truck?
do a compression check..did you happen to nick the coil harness where itd receive a poor signal?
plugs gapped correctly?

 

100k warranty! If its not highly modded that is.

 

intake been off? over heated? Head gasket? what did the plug look like?

 

replaced the plug, not sure if it had been gapped right out of the box. used a ACDelco plug. intake has not been off that i know of. didnt check head gasket yet