Bear with me on this one. Several weeks ago you'll remember that my throttle body failed which contributed to an overly rich condition and plug fouling. I replaced the throttle body (with the Ford Racing 62mm) but the car still struggled, hunted for idle, surged to 3000 rpms with no gas & had unusual extremes of lean/rich. First I thought I had a bad vacuum leak but I quickly ruled that out. I then replaced the thermostat (which I know contributed to the overly rich condition), fuel pressure sensor and both front O2 sensors. Still no success. Today, as a last resort, I replaced all of my coils and that finally resolved the problem. I apparently had one or more fail with no DTC codes. Anyway, 3 weeks multiple parts, and $1100 later, she's purring like she used to. And I was just about to throw in the towel.