Hi....I'm having some trouble tracking down the source of a recurring 'P0306' code. The car is a 2003 GT with 60K miles on it, and I started getting a very rough running symptom (especially when warm, and under a load) and then the computer coded. Sooooo I replaced the coil in number six, that seemed to fix the problem for a week. Then it happened again. So I swapped that new coil with the coil in number five, and it happened again. Cyl. six. So I figured the coil was ok, swapped injectors between five and six, it happened again.
I put new plugs in all eight, as well. Any ideas? Argh.

 

Here… Let me google that for you…

Did you check your plug wires?