How would extra air fowl out a plug ? If each cylinder had its own o2 senser yeah but no.This car is stock with stock type ac delco plugs which easely go for 100,000 miles in stock trim. But thanks for the info on exhaust that helps my buddy told me it may not have manifold gasgets,was hoping for an easy fix.My car has 212,000 miles why would it ping and have a slight vibration when you slowly accelerate but if you hammer it it runs well not like the cats clogged.Does it have a steatched timing chain and have to much timing, burnt valve.I'v drove this car for ten years sence it had 21,000 miles on it and really like it I would hate to have to buy another gtp lol. Im disabled and cant do things like a few years ago otherwise id tear into it. Thanks for your thoughts on this.