Hi scotty how are you? I have a check engine light on my 2007 buick lucerne with the 3.8 liter v6 and it says emmissions control circuit. I just cleaned the egr valve, throttle cleaning and maf cleaning. Also my transmission clunks at heavy throttle applications, shifts excellent. Is it my mounts? Also what about spark plug gap. I always use iridium spark plugs. I was thinking of altering the gap. For better mpg.