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.

do not alter the gap, period. Emissions are complex , so find a guy with a dealer scan tool to analyze the system, or heck, try a new gas cap first. Pray your cv joints or motor mounts are making that noise, and not the transmission itself which it often is on that model, sadly.

Oh boy. Thank you soo much scotty! Your a life saver!