(John Galban) wrote:

I think there's some confusion about your troubleshooting. In the
original post, I (possibly by mistake) assumed that when you switched
to the rough mag, the #2 EGT "shot off the scale" to the low end (i.e.
cold). If you're saying it shot off the high end of the scale, this
would not be the kind of reading you'd expect from a cylinder that is
not firing.

A weak spark rather than no spark maybe? If it's firing but less
efficiently?
My understanding is that this effect also causes EGTs go up when
running on only one mag.