DPG3

The plot thickens with the check engine light and the 306 code. I have replaced the coil pack ( genuine Motorcraft ) and local parts store verified / killed code. A week later the light came on again--same code.Had it reset and I had several fill ups but added a bottle of Chevron injector cleaner each time. Light stayed off 3+ weeks this time, just came on again during acceleration getting on freeway. Do you think the #6 injector is the problem---plugs, wires, coil pack all new--what's left . Thx. Tom R