Originally Posted by
carta79
Are you checking your plugs after a part throttle run (city driving)? Take your car as close to redline as you feel comfortable and check your plugs right after. 
I checked after about 300 miles of driving, I commute 60 miles a day, fwy driving, and I also do some city driving. When I city drive tho, I smash on it :shhh:, close to redline. Well I will do what you said, and check them. However I noticed that once the plugs turn black, they don't go back to brown if you fix the af mixture, do they??