running problems

[usmcgtstang2141]

hey guys got a problem before i left on my deployment my mustang started running rough. ive gotten back now and im having trouble diagnosing what the problem could be!!

while it's running i get an intermittent loud pop in the exhaust
i have 2 misfire codes that come up too, even after replacing plugs they are cylinder 4 and 8
ive checked the coil pack they are firing and the wire is good too both cylinders are on the same coil pack.
the car seems to run real rich

please give me some help not sure where to go from there:shrug:

 

[usmcgtstang2141]

well my buddy checked it out of all things it was the MSD wires! the boot portion went bad and was arcing all over the place in the hole instead of to the plug!