Unregistered

Well being a Ford/Lincoln tech I think I may be of some help. Most likely you have a bad coil.. although the chances of it are high that it is #6 for your P0306, its not always that way. Sometimes when a coil goes bad it emittes whats called RFI or radio frequency interference. In other word, your computer or PCM, controlles your coils and everythin else on the engine. When a coil emmites a strong enough "radio signal" from the charge and discharge of the coil, it can make the PCM go crazy and make other cylinders misfire. I have seen coils make the vehicles stall out for no reason etc. But more times than not its just that #6 coil.

The response about the vacuum leak although they do experience those leaks, it wont cause that misfire and your code would have been accompanied with a P0171, and or a P0174, lean codes.

Then there is the possibility of having a burnt valve. A burnt valve will cause your P0306 but generally you would notice a constant skip and it wouldnt be random.

Hope this helps