I have a bad mis from 1 to about 2,300 rpm or whenever i smashed it to the floor after that...it will clear out when its about that rpm and i'm just cruising...Is this the Opti-spark? I'm not very fimilar with it. I put all brand new plugs in and all the wires are fine. I installed my jet hotts and still dont have my O2's all hooked up yet...but it ran fine for about a month after the installation so i dont think those have anything to do with it

 

Check to make sure your wires aren't too close to the exhaust.... mine started having a bad miss last week under the same conditions you said. It's about fine under very light throttle, but as soon as you give it a little more it starts missing like it lost a cylinder. Was pissed b/c i thought the opti or a plug was going out. Got to looking under the hood with it running and giving it some gas by pushing the TB lever.. could see about a 3/4" long spark go from a wire to the no. 6 primary tube.

Moved the wire back a little bit and the miss went away completely. HTHs