Rough idle... only when warm.

Jonathan Bass said

Trying the spacer and gasket today.

I have a new MSD Blaster coil, new ballast resistor on firewall, new voltage regulator, and original distributor that it had when I bought the car.

Problem existed with previous coil, ballast, and regulator.

Will check fuel pressure.

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Cold fluid flows slower than hot fluid. (soft shifts when cold) and trying to compensate with idle speed because of a rough running motor can cause harsh shifts, so for now just deal with the running quality and the shift engagement issue will probably go away.

Sounds to me like the carb is going lean when the choke comes off as it warms up.
As mentioned above once its warmed up and running crappy try using your hand to cover part of the top of the carb to restrict the air going in.
If it runs better as you restrict it tells you it’s lean.
It also works to point out a rich condition, as the restriction causes the motor to run worse.