[RH77]

I'll tell ya -- if it wasn't for the engine block heater plug-in, my tank average in the cold Winter would be about 5 MPG lower. (This is the direct, factory addition).

I too suffer from auto-trans, Arctic inefficiency. The torque converter is VERY hesitant to engage, and it won't upshift lower than 2500 RPM after a cold-soak start.

Since the rad has a built-in tranny-cooler, I assume a quick burst of warm transmission fluid is sent through the system on startup after plugged-in. That's it, I bet.

My guess is that your TC is acting-up in the cold. It can engage and disengage without change in speed, but the engine effort changes. Chrysler trannies are pretty particular to cold. This is followed by foreign brands, and finally by GM (they'll lockup at -40F, 2 miles after startup). Ford? Well, it varies...

RH77