Some possibilities based on my own experience and what I've read here:
Bad fuel pump - have you noticed any difference if the tank is close to empty or full? If problems only happen when the tank is more empty than full it could be a pump on the way out, or even something more simple like the filter.
Bad plugs/wires - This was the problem I had. I installed crappy splitfires before I knew any better. I had hesitation only on the freeway (75+mph @ 3000+rpm) at WOT. Going WOT on the street from a dead stop didn't have a problem, all the way up to redline. Changing to Autolite double-plats (which are recommended) made all the difference. If you're already running double-plats you might have one or more bad plugs. Bad or frayed wires can do this also. It could also be the coil pack. If you can isolate the problem to be an ignition one, the best path is to replace plugs, then wires, then coil pack; based on cost.
I could also be way off here, since the problem you describe is similar to mine but different, but I figure any suggestions you can try would be better than none.
