asilverblazer,
Obviously a sooty plug on a single cylinder tells you that it is missfiring for some reason. Fuel problems would involve all cylinders and plugs.
Basic sleuthing would require a compression test and a look at the valve train. The ignition system with it cap and wires could cause problems specific to one cylinder only.
A good basic tune up, timing check and the above mentioned items would narrow down the problem.
The coil is know to be temperture sensative as well as the valves. Too tight and one might not be closing all the way as things warm up.
A vacuum leak in a intake runner could cause problems too...there are so many 'maybes' that you need to do the basics to wipe all the variables from the chart. Do a full tune-up, run the valves and do a compression check. You will cure the problem or narrow your search so you can pinpoint it more easily.
Stuart
