you will always have some build up on the plug.. even if it has been ran for just a few days.. the times when you have to be worried is if the build up is only on a few of the plugs and not all of them.. this will tell you that a certain cylinder isn't getting everything right.. spark could be too hot/cold.. too much fuel or too little.. poor atomization of the fuel.. and so on...

My advice is to isolate the problem to a certain cylinder. The misfire will probably be in a certain cylinder. While the engine is idleing remove one wire at a time and see if the RPM goes down. If there is a cylinder that dosent affect the engine RPM when the plug wire is removed then start there. Give the motor a compression test. If that cylinder is a lot weaker on compression than the other ones than you may have a serious problem. If that cylinder has the same compression it will not be that serious. Make sure you read the plug carefully against the other ones. Then I would swap the fuel injector with another cylinder injector and see if the motor loses RPM when plug wire is removed. If the RPM goes down than it could be a bad injector that was in that cylinder. However if it was a bad injector then the cylinder that you swapped the injector with will now have the problem and it wont change RPM when plug wire is removed. This will pinpoint the problem of a bad injecter before you go out and spend money on a new injector. However if the same cylinder dosent change RPM after swapping injectors then you know it is not a injector problem and look into ignition wiring.

Nice chart. I'm gonna steal it.

I think everyone should, i know i will.

It's inside every Chilton repair manual. (Is it Chilton or Haynes?)

i just googled spark plug chart.. the link is posted up on another forum somewhere else.. it is a good chart tho..

it is also in my online photo gallery

There's your problem, pull those POS plugs out of that motor and replace them with Champion Coppers (Cheapo $2 plugs) and gap em .045 on the 4.7L I think).

nah its still .040 on the 4.7 hydra

Yea. I actually did that and am still having the same problem. Hence the thread name

I did pull it in the garage yesterday and while the engine was running, unplugged each coil one at a time. The weird thing is that I didnt notice any change in idle at all! Not for any of the cylinders

What do you guys make of that? I don't understand it...

Thanks again!