G.R. Patterson III wrote:

Make sure you check the wiring harness too. Last time I had this sort of
problem, one plug was fouled *because* the other one wasn't firing and
she was running too rich on that cylinder. The other plug wasn't firing
because the plug wire had quit conducting electrons.

George,

How would you check the wiring harness?

As of today, Tigger was running like a Tiger and purring like
a kitten.

EGTs were lower on ground run too.

So we'll hope it was bad plugs, but my "we haven't gotten to
the bottom of this" warning is still beeping in the back of my
head.

Cheers,
Sydney