Ford Crown Victoria misfiring after spark plug change, What could be the cause?

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Codes: NA 101, P0306, P0307, P0308 I have a 2001 crown victoria that is misfiring on 3 cylinders: 6,7,8 So far this is what I have done: replaced all 8 sparkplugs replaced two coil packs on cylinders 7 and 8 (1st cylinders misfiring) After I changed everything I hooked up a scanner and now cylinder 6 is misfiring When I changed the spark plugs on cylinders 7 and 8 there was brown liquid on the plugs I have not cleared the 7 and 8 misfire codes after replacing plugs and COPs to see if its fixed, but the car seems to run better after changing everything (used to idle roughly). The car was sitting for 6 months when I brought it but the tank was near empty (fuel light on) The car has a delayed acceleration/lack of power but will accelerate to over 80 and the CEL flashes when I accelerate over 45mph.