Did you put new wires on too, or just plugs? Check all 8 wires for a good snap when you put them on, or just pick up some Motorsport 9mm's.
As far as plugs go, I run champion coppers (forget the model #) at .054, and they're great. No need for platinums on these motors.
The bucking, hesitation and power loss all sound like you are getting bad spark of have a dead cylendar. How'd the plugs you pulled out look? My stock wires were bad, one didn't snap down, and it sucked real bad up on top. I thought it was my fuel pump, but it turned out to be a wire.
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1997 Mustang GT "The Freak" - 13.80 @ 101.70, 2.07 60'
1995 Honda VFR750 - not much @ really fast (actual data pending.)
1964.5 Mustang 289
Rice Haters Club Member #13