02 f-150 4.6 misfire help
 

A buddy of mine has a 2002 F-150 2wd 4.6 sohc. It threw a code for misfire on cylinder 6. The dealer told him it was the coil. Well we replaced the coil for #6; next day same code popped up. Anyone have any ideas as for why it did this? I plan on switching 6 and 7 coils to see if it moves or not in case we got another bad coil or to see if it wasn't the coil at all. Also, I changed all the plugs. Number 6 didnt look bad on the combustion side, but was red on coil side. There were also 3 plugs on the driver's side that the theads were coated in oil and looked like shit. I'm pretty sure they were the stock plugs on an 8x,xxx mile truck.

Any help is appreciated. Thanks. - Todd