What can you tell from these plugs?
 

All of my plugs look like the top one. The one nasty one is the #4. Last time I ran the codes I did the balance test and it came back that 4 was bad. What am I looking at here?

http://www.mustangworks.com/cgi-bin/...dia.cgi?1056+3

Thanks for the help
Chip

The top plug looks slightly lean, and the bottom one isn't firing. Check the resistance in the plug wire.

Take care,
-Chris