Not sure I quite understand re the cam sensor at cylinder 3, do you mean there was no spark at plug 3 when there should have been If so see if the coil -on- plug works for no. 3 if fitted in an alternative position , say no. 2 position. Have you also checked the head earth, small bolt at rear of the head. I have seen them with brown or black wire connected. also do a continuity check with the plugs fitted. First check that the earth connection between the body of the plug and head are good, then check the plug electrode top connector is not earthed with the head, ie a shorted plug through an internal breakdown, this will have more of an effect than just causing one cylinder to stop working.
Again, when the engine is turning over is there fuel reaching the cylinders, and when you first turn the ignition on can you hear the fuel system prime to pressure then stop? there has to be either no fuel or no spark Unlikely that you have lost both but not impossible
