2006 Roush Stage 3 with 52,000 miles. Changed spark plugs and about 2-days later check engine light came on. Code indicated coil problem on #3 cylinder. Cleared code and it came back after short drive, did this about three times. Decided to replace all stock coils with Accel Super Coils, now light came on indicating problem with #1, 2 and 4. However, car is running great. Can't figure it out.