Hot 170

Welcome to the site.

First, the thermostat has absolutely nothing to do with controlling how hot the engine gets. It simply controls the engine's minimum operating temperature. You are better off with the 180, or even a 195. Whatever the Factory Service Manual calls for, that's what you should use.

Both hoses being hot indicates nothing about radiator flow. That simply means the engine is heating up the coolant, which it will do even and especially if the radiator is stopped slam up.

You can try flushing it yourself, but usually it's better to take it to a radiator shop as they can make any necessary repairs at that time as well.