Answered on other thread.
If you remove a lead and it even ALTERS, then that cylinder IS firing, as if it were DUD it would still be dud.
I would firstly change the plugs, as one may have a high resistance, or a lead.
The phase sensor will NOT cause a particular misfire like this, unless alignment was out, it then would pick on the weakest cylinder, check for a play in the shaft as these are not unknown to pick up the bush and spin in the housing.
I would also do the usual look for air leaks, as this will affect the waekest cylinder firtst.
tabetha