How do you know if a coil pack is going bad? My 96 Tbird w/4.6 runs fine till it gets warm and then its like the car only has 4 cylinders. But its only intermittent, it will cut out for like a tenth of a mile then run right again. Ive had it in one shop and they repaired a corroded ground wire to a coil pack. Two days later the same problem happened again. Back to the shop and they replaced some spliced wiring. Now two days later, same problem. Ive jiggled wires and unplugged both of the packs one at a time and it runs exactly like it does intermittenly. Anyone ever had this problem, or are they just going bad? Thanks for any insight on this one, its driving me crazy.