petrified.rabbit:

The "bursts" happen daily. Recently the check engine light came on due to a faulty O2 sensor and it was replaced. I don't think that's it. The car just turned 40,000 miles and I'm quite sure that the plugs are original. I'll take a look at them tonight.

Thymeclock:

My wife has had the car since before we were married and when I asked about the warranty she said it was expired. I assumed it went to 30,000 miles, maybe I'm wrong. Was the check engine light illuminated before your pedal was changed?