I need some input on a spark knock issue under light acceleration for my 2003 4.8, manual trans silverado. Went to 89 octane. Changed PCV, plugs, clean air filter. Will a bad knock sensor cause it with no CEL? Been chasing this for years. Is the winter gas causing this. I forgot what it is but the octane rating changes because of temp change. i think. Thanks and please give me some kind of help.