Here is what you don't want to see on WP - wobble, eats aluminum, calcium build up. Keep bolts in order, the lengths vary.

 

Thanks Savannah, the WP looked great, the impeller had a few specks of copper on it as if the PO had poured some kind of stop leak in the system.

Anyway I got the new radiator in and the problem is without a doubt solved. The ODB scanner will show up to ~200 F for a very short period as it warms up, but once the tstat opens up it'll never get above 180 or so. This is just idling, with heater or A/C both on and off, haven't taken it out for a drive yet. I think I can say I learned a valuable correlation through this troubleshooting.

If the engine overheats even at idle and you have these conditions:
1. heater off while idling = overheat
2. heater on while idling = overheat
3. heater on while revving = cools back down + *extremely* hot air through the cabin vents

Then:
The radiator is not sufficient to cool the system and pushing more water through the heater core by running the water pump at higher RPM was acting as a sort of back-up radiator.

Thanks again for everyone's helpful posts!

 

I know this is an older post, but thanks anyway for everyone's detailed responses. I'm learning alot about my overheating issues.