i'm relatively new to the forum thing and this is my first post on here so sorry for the lack of SOP
anyway, i've got a 2000 extended cab silverado with a 5.3 and about 190k on the clock. I've kept up with all maintenance over the past 6 years that I have been driving it. about a year or so ago, i started noticing that the engine would ping/knock at higher rpms and when under a heavy load (towing our boat) it doesn't throw codes or anything, so i started filling up with premium gas and the problem went away. fast forward til about a month ago, it starts doing it again, in spite of the premium fill-ups.
the only code i have is an occasional bank 2 running lean code.(i dont know the number off the top of my head) by occasional, i mean that if i clear it i can sometimes drive a solid week or two without it cropping back up.
within the last 6-8 months or so i've replaced the fuel filter, done injector flush, plugs and wires, and new knock sensors. most of which was just in the course of normal maintenance, but all of which have seemed unable to cure my issue. i also tried seafoam, to no avail.
oh btw, no vacuum leaks that i can find and fuel pressure is good.
the only other place i know to go is the upstream o2 sensors, but am not sure that it will fix my problem.
any suggestions are welcome and appreciated. thanks
ps, mods are: true dual exhaust through flowmaster 40's (stock manifolds) and K&N CAI