[wiswind]

You might try a new radiator cap....as cheap as they are.
Mine gave me problems in maintaining pressure......I had to keep messing with it as I kept finding that it was not holding pressure.
I got the normal cap.....no pressure release thing....just one that was just like the OE one.

I don't know if a new CCRM would help or not.
Only way to know is to change it.......more money....but then it is old.
Mine needed replacing 2 times......the 2nd time was because the A/C relay was not holding the A/C compressor on.....following the A/C cycling on and off a lot when the A/C charge went down......due to a leak in the evaporator coil.
So....the CCRM might be worth a try.

Another test.....you could try unplugging the radiator fans VERY TEMPORARILY to see if the stumble still happens.

The tranny cooler inside the side tank......on the passenger side of the radiator and the tranny cooler in front of the radiator (if equiped) both have ONLY transmission fluid flowing through them.
Inside the radiator......the coolant flows OVER the fins of the tranny cooler.