[Speedbumpauto]

In spite of what racers may tell you, Holley's don't like 7 pounds of fuel pressure very well, especially on the street. You need to make sure to regulate the fuel pressure to around 5 to 6 psi. Sounds like your float level is marginally wrong (high) or the pump pressure is slightly over riding the needle and seat and in periods of low fuel use, like cruise, it has enough time to raise the fuel level in the float bowl enough to where the main circuit starts bleeding fuel in addition to the transition slots where the engine wants to run. As soon as you pound it a little, the fuel level drops slightly due to increased demand and everything cleans up until the next time you cruise too long and it happens again. Make sure you set the float level by the sight plug correctly and use a regulator and gauge to keep the fuel pressure in check.