After a soaking rain last week, when my car started sputtering and running very rough with a CEL, the dealer replaced the spark plugs and "resistor tips." The car used to have some flat spots at low-RPM, so I am sorry this took so long to become obvious. Some of you may be familiar with some ongoing posts of mine about what I thought was an occasional-but-persistent transmission slip at launch. The symptom was a jerk and stumble, which in hindsight I should have known wouldn't be trans-related. It also was never able to be duplicated by the techs.

Well, when the plugs got replaced, the first-gear/launch stumble went away.

What this means is, for 20k miles the car has had failing resistor tips, and though the plugs were replaced at the 60k pre-sale service, it has never performed properly.

Is there any effect this long-term misdiagnosed condition could cause to the cylinders?