There are TWO coils on EACH coil pack (four total), and as you can clearly see...4 & 7, 5 & 8 are both on the SAME coil but on different coil packs. Change the coil packs.

 

Would you mind saying that differently? In looking at the above diagram from Boston4, I am seeing they are on different coil packs... but I didn't quite follow they are on the same coil...

 

l'll try this one more time...

There are four coils, four, and there are two coils on each coil pack, two, two on the DS coil pack and two on the PS coil pack. You can clearly see in the diagram...four rectangular boxes, each rectangular box represents a coil, with two numerals in each box that represents cylinder #. In the diagram, there are two rectanggular boxes for each coil pack, upper and lower. One rectanggular box has #4 - #7 (DS coil pack - lower coil) and that is the coil for those two cylinders. Same goes for the box with #8 - #5 (PS coil pack - upper coil), it is the coil for those two cylinders.

So, we have FOUR coils (total), TWO coil packs (total), each coil pack has TWO coils within its housing (one upper and one lower), there are TWO cylinders pre-coil (# within rectangular box in diagram).

Just change the coil packs and wires and you'll probably solve the problem. If original...they are 17 years old...that's like 90 in human years. Bad wires lead to bad coils...over time...the resistance from the bad wires causes the coils to work harder to maintain strong spark...and after a certain amount of time...they just give up. It's kind of the way l feel at the moment...lol.

Good luck.

 

Replaced the coils with Bosch, Wires from STI, and NGK Iridium. In doing this, I did see the old STI wire on cylinder 4 was broken at the boot, which corresponds with the most recent code read I got. Replaced everything, filled up with 93 Octane and all issues gone!

I removed the plenum to take out the coil packs and frame, lay the wires out nicely, used silicon grease on everything for easy removal. Relatively straight forward, just takes time.