[jtf914]

I had the same problem when I was learning to tune my webers and adjust my timing.

Try checking your fuel pressure, I added a regulator to keep the pressure around 3-3.5lbs, I don't know if this was the real solution as I was changing more than one thing at a time, but my hypothesis was that the pressure would build while the car was sitting there idling which would eventually force gas past the needle valves, flooding the bowls causing the RPM's to start rising.

Good Luck,
Justin