Spark plug gap may need to be checked or adj.
I installed back the +4 ignition advancer because I just can't stand the stock ignition response...Like you said it didn't move for a split second and your right. I'm going to try run on premium 92 see how it turns out. I notice my engine burns hotter now with the +4 advancer.Um maybe you you should have switched to premium. I don't know enough about engine physics to say why but when I installed my advancer (quite a while back) I also had hesitation; very slight, barely noticeable, I only picked it up cause I glanced at the tach on the track one day and noticed it didn't move for a split second.
Well, after a bit of trial and error I switched up to 98 (which should be 93 or 94 stateside) and it immediately stopped. Every now and then on long trips when I don't have a choice I use the normal 95 (91 US grade) and it'll occasionally sputter.
My friend who has a 2002 also installed an advancer last summer, he hasn't noticed any problems with using the 95 fuel, but said that he has noticed a difference when using 98 or 100 which wasn't noticeable before putting in the advancer.