Here's what I did recently... I bought the Durametric, and showed Cyl misfire #5. So... I swapped coil pack between cyl 5 and 6 and guess what??? The next CEL code threw a Cyl misfire in number 6. Bingo!!!
So...
1. read your code on the Durametric
2. swap coil packs on adjacent cyl AND...
3. swap plugs on OTHER adjacent cyl
4. clear the Durametric code
5. drive car, run engine up to the 4k+ RPM
6. let engine cool, drink a beer (or two)
7. read the code again and see which cyl the problem follows
8. order parts
9. take girlfriend out to dinner
This procedure took me an hour or so. I'm assuming you have ignition issue, and guessing a fouled plug. My coil pack issue wasn't rpm related, it was intermittent. I hope this helps.
