Retuning (Converter Replacement?)
is not too distinct into a slushie donut of a converter.
For diagnostic purposes set all the misfire tables to 32767
and see if the symptoms go normal. If so you could go and
work the original values up to where they stop "detecting"
on you. Also things might get better once the cam is dealt
with. But even with stock cam I had to kill misfire detection
for my present converter (and I just left it killed although
I'd prefer some detection for gross problems).

