My car has a misfire on cylindars 2, 4, and 6. What could cause this?

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This happened all at once after the car went over a bump. It seems it has to be something in common with all 3 cylindars. I have checked: oxygen sensors upstream, cylindar compression, spark plugs, spark plug wires, coil pack, fuel pressure, vacuum leaks, CKP, MAF, EGR, IAC, PCV, TPS, Variable Resonance Indiction System. I have replaced: fuel filter, fuel rail, injectors, spark plugs, coil pack. I did find that the cam sprocket for that bank of cylindars had jumped a notch and corrected it. I am not a car expert. I just use my Haynes manual and have good troubleshooting skills. This one has me stumpped.