I have a 2002 Escalade, as close to stock as it gets, only mod is a true dual 2.75" exhaust and a 25hp tune from well known handheld brand.
It is sometimes knock retarding madly around 2k under mild load (for example around 16 sec into the log).
What could be the problem here?
but on the other hand I think the good ol' truck is performing quite well, still hitting 0-60 in around 8 sec, after 120k miles!