What was suggested in the beginning..manifold gasket..the computer is probably trying to compensate for the extra air and dumping fuel. You can rent fuel pressure test kits for free. This will tell you if you have a fuel pump or regulator problem. It wouod even show a leakimg injector. You may have a fuel leak. Cylinder 7 and 8 aren't on the same bank. What they do have in common is they both on either side at the back of the intake.
All I want to know is how in the hell do you improperly install a sparkplug?!
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