I just recently got an 2000 v6 mustang. It started missing a threw a code so i brought it to autozone to get it check. It said misfire cyl 6. So i had the sparkplugs, and wires changed. The light went off and it was fine for about a day and the light came on again. Got it checked again it said misfire cyl 1. So i had the coil pack changed. The light went off but the car never stopped missing. Its missing between 1000-1500 rpms. Any ideas of what it could be?