The miss fire does come and go. The last race we couldn't stay out of the way so he brought her in. When it came time to load her in the trailor, the miss fire was not there. I am possitive it is a miss fire, I just can't figure out what is causing it. My son told me when he eases in to the throttle it is fine until he floors it for the straight. It is almost like it is ok in the two barrel but when requiring the four barrel it misses. However, do not take that last comment out of context as we only have a holly two barrel on the engine.