I have been getting KR on my grand prix for a while now not to much but its still there. The mods I have on the motor is a 3.5" pulley, 2.5" catted downpipe, K&N air intake, 180* stat, Overkill pcm and I had switched the plugs to a TR8 super cold plugs to try getting rid of the KR but still has some on the highway. I was wondering since there is a little bit of noise coming from the lifters I think but could that cause KR? I have noticed that when on the highway at cruising speed the bogging down will kick in then when starting up a hill the rpms will bounce then climb with the accleration and that when I see KR. I also think there might be a vacuum or intake leak but not sure. Any help would be great because no one in my area does scanning or tuning. Thanks!