03 marauder 300a is now spark knocking under light/ moderate acceleration, she has 109k miles I pump 93 from chevron and Exxon, I have changed out the spark plugs didn't solve the problem, cleaned maf, changed out air cleaner , replaced egr valve, still pinging , tried seafoaming it no results, how do I know it's spark knock? Mhm it only pings when full operating temp , no engine light is on, took the car to a mechanic hooked on the computer and said everything checks out good, stock tune stock thermostat .. What's my next step??