Well, if you are still looking for info on this, I'll throw in my two cents.
First, you ask if a clogged cat-conv can cause a misfire. While I've no doubt that the back pressure caused by a clogged CC could
cause a misfire, it seems unlikely to me that it would be so repeatable in one cylinder. Then you have to consider what caused the bad CC to start with. Interestingly, two of the biggest culprits there are repeated misfires and a bad bank one O2 sensor. Both can create overly rich conditions resulting in the failure of your CC.
At this point, I would stick with assessing the injectors and go from there.
I believe it would be rare for you to find that the ICM was causing a misfire on one cylinder only, but checking it is not that hard.
And...not to be chicken little here....but you may very well be experiencing the beginnings of UIM and or LIM gasket failure. Some here have had extremely similar symptoms as thiers failed rather slowly. This can also lead to a clogged cat/conv.
Others experienced rather sudden UIM failure. Hard to say.
Get those injectors checked out and lets go from there.
Mike: 1997 SE w/ 183K, aka White Horse
, Gutted Airbox w/K&N, drilled 180* t-stat, tint all around, clear corners w/SilverStars, "PONTIAC" light up tail, PEMs, NGK TR55s