I replaced those when I replaced the upper and lower intake manifold gaskets. What I've learned about the damage to the 2 plugs I show above is that they indicate a lean condition. I added BG injector cleaner to a tank of gas and there seems to be an improvement in throttle response. I haven't driven out the tank yet to check mpg, but it may have been clogged injectors in # 4 and #6. Interpreting how replacing the plugs may have brought on the loss of throttle response is a little difficult, but it's possible the ECM was compensating for the lean condition by dumping more gas and didn't re-calibrate. I'll know more after I run the second can of injector cleaner through the engine.
