[valiant67]

These cars don’t have a lot of excess cooling capacity. My bet is on the radiator too.

 

[valiant67]

If it was a problem with the viscous fan, the car should run cool on the highway and heat up at lower speeds. That's a good idea that's easy to test.

 

[valiant67]

Do you think to get me by until the new one comes I could pull the thermostat to help it flow more through, or would that just make the problem worse from moving coolant too quickly through the engine, not so much the radiator?

All removing the thermostat does is change when the overheating problem occurs. In my opinion, it's never a useful option.

Rather than remove the thermostat, I'd spend money on faster shipping.

 

[valiant67]

If it is indeed the radiator, about the only temporary thing you can do is to put the heat on full hot with the blower on high. The heater core actually functions as a small radiator.

 

[valiant67]

Didnt the OP say a rad shop cleaned the rad and said it was in good shape?

Yes, though there was a picture looking through the cap opening and it was still scaled up.
The OP did replace the radiator which solved the problem. The 400 in the Cordoba had a single core radiator that didn't have much margin for error.

 

[valiant67]

I think I would find a different radiator shop.
Heck a 318 needs a 2 row unit.

You know, the 400 may have been a 2 core? It's been years since I had one. But as soon as it started to scale up, the car wanted to run hot. I wondered if the HP 400 got a better radiator than the regular 400.