I mentioned in another thread that I swapped in some non-resistor NGK's the other week as an experiment to see if there was any difference in performance. I also gaped them at the high range of the spec, .032 or so. I observed quicker starting, not that it was objectionably slow before, and a slight hesitation off idle that was more pronounced when cold but still there when warm. I suspect this was due to the plug gap, eventually I'll test my theory.

For now though, I cleaned the resistor plugs (that had maybe 2K miles on them) and gaped them at .028, the low end of the spec. I observe slower starting, though again not objectionable, and the hesitation is gone. I think, though it's my seat of the pants-o-meter, that the midrange throttle response is better, but it's hard to tell on a stock automatic NA B230 it's so soft in general. But the hesitation seems to be gone.

If it wasn't the ole lady's car, I'd buy an MSD or Mallory ignition box and high voltage coil and open the gaps up again and see what happens. .028 is really, really small. A good HEI in a 70's Chebby will fire one 3x that wide happily, with sloppy carb'd mixture no less. Seems there ought to be room for improvement.
No real conclusions other than that, just observation. And I can't remember which one, but I had another gasser car that responded this way to plug gap as well, might have been my last turbo volvo, not sure though.

No difference in the crappy idle, btw, that still get's worse as it get's hotter, sitting in a drive-through or such. I wish it would just crap out completely so I could find what is acting up, such is Volvo life though I guess.