misfire code P0300

What is your question?

it started with a P0306 misfire code, after we found plug wire 6 arcing off the O2 sensor, we moved the wire and the car is running fine now but the code changed to P0300, random misfire, we changed the crankshaft sensor//the coil packs(where the plugs go in, all 3 replaced)and replaced all the wires as 6 had a burn spot on it from the O2...now when I hit 40-45mph and the RPMs hit more than 2+ the engine light blinks (gradual speed with low RPM no blinking of the engine light, just stays one steady) I am fit to be tied with everything I have done please anyone help! The car is running fine no misses or knocks or nothing, idles great and runs great I'm so confused about this.