Hello, recently my 2007 GMC Sierra 1500 5.3L NNBS has developed an issue While driving at relatively low speeds there is a distinct pop sound when switching out of V8 and into V4 mode. it is intermittent and only seems to happen while traveling under 30 MPH. I have been doing research regarding AFM and lifter failure and wondering if this is related and if so is it too late to do anything. Would an AFM disabler do anything at this point or am I looking at a complete rebuild in the near future? There is currently no check engine light and no codes are being thrown.