Short story...I bought my 99 GT about a week ago and the next day it started missing, I posted a question here about it and everyone said it was the COP's, went to Autozone for a scan and had a misfire on #6 and #7 cylinders, bought 2 COP's and the miss was fixed but they didnt fit right and it ran bad for the 1st 15 mins in the morning, Autozone got me a different brand and same thing. I went to Carquest and the 2 they had were the same as the other ones however Carquest looked up COP's for a Crown Victoria 4.6 and they were the right fitment for my car, could my engine have been swapped or maybe aftermarket COP's are not made correct for Mustang 4.6's. Any ideas anyone?