Heres the deal 99z heads and cam motor, never had an issue before. Car was running awsome, then it created a miss/surge type cond. Pulled the plugs from the drivers side all 4 look as new as they did a month ago when I put them in, Passenger side all 4 plugs are 100% BLACK looks as if ALL 4 were running very rich, I am sure this is the reason for the miss/surge. What would cause this? Going to replace the plugs on Sat. but would like some ideas on this before hand. The filter was extreamly dirty, and I know he has been driving around alot with the dump open, but I just dont see this causeing it. Any help or ideas would be great. Thanx.

 

Hmm, black plugs on 2, 4, 6 and 8 cylinders... I would start with the basics like replace your air cleaner, and maybe do a cylinder compression test. It could also be worn out valve guides seals or even a bad coil. Maybe take one of your good plugs and replace it on the passenger side and if it fouls too then you could have leaky injectors. Just a couple of ideas...hope that helps.

 

Replaced the O2 and a new set of plugs, Everything back to normal.