Rough Idle in this hot weather

I am running a 200 6 cylinder in my 61 Ranchero. I still have the original Fordomatic automatic transmission in it.

The car runs great except....now that we are in 95+ degree weather, after high speed driving for about 10 miles, the car idles very rough (stumbling, missing, etc.).

As soon as the light turns green, the car accelerates without hesitation and runs great at anything above an idle speed after it warms up.

I will say that when cold, it idles fine, but does have a little bit of "rolling" or stumbling, but not much. I am running an Autolite 1100 carburetor with manual choke.

Any ideas?

Hi, It may be flooding, I wonder if it runs better if you hold the idle up a little or drive with two feet. Maybe the float adjustment is off, or a sticky needle and seat. Check your air cleaner first. good luck

DOES sound like 'fuel' (but ck the coil for 'too hot' condition).
Wonderin bout 'heat sink' in the carb too.
Change the fuel filter 4 a cheep try?

What do you mean by coil "too hot"? I am running the Pertronix ignition with their "Flamethrower" coil.

To determine if you have a fuel issue or an ignition problem, hook up a timing light & see if the timing mark jumps around. If the mark goes spastic get rid of the pertronix.
Another way to test the pertronix is remove the cap on a cold engine & heat the pickup with a hair dryer.
If problem exists the heat will trigger the issue. Bill