Sporadic Low RPM Problems

[riversz]

I'm having a really tough time with a very sporadic low rpm miss with my 1971 Z. The engine, carbs. and ignition are totally stock except for a Pertronix ignition I installed last August. I doubt thats the problem since the miss which can happen at any time whether the car is hot or cold, just started occurring last month and it occurs just out of the blue. The car can be running just perfect, it always idles just right then as I pull away from a stop it will hesitate and stumble until the engine hits about 3000 rpms where it clears up completely. If I hit the throttle hard as it begins stumbling it really bucks, but if I'm really careful and let the rpms build slowly the stumble is minor but there. I've checked plugs, the distributor, cleaned the rotor and cap, checked electrical connections and I still get this problem. I suspect maybe a problem with a carb, maybe something sticking or a dirt problem. Any ideas or has anyone dealt with a problem like this???

Thanks

[Ed]

What is your timing set at?