Trying to sort out some swap cooling issues... Options

[aspen]

I've still got some cooling issues on the BEAMS.

Here's the deal, I've got a new radiator, new OEM thermostat, new hoses, new water pump and new temperature sensor. (I want this swap to run for quite a while).

Still have some cooling problems though where it'll run hot, and the temperature gauge will behave somewhat erratically. I hooked up OBD to it and the ECU reported around ~95C with the needle close to the red. Of note, I tested my 82C thermostat and it opened, but maybe a bit higher than 82C (it's not the most accurate thermostat in the world) but it still seemed maybe a bit strange?

I'm pretty confident the system is completely bled, and heat works. The top radiator hose gets hot but the bottom one less so (though, shouldn't the coolant going into the engine be pretty cold anyway?)

I ran the engine briefly with no thermostat and just water and it also got surprisingly close to operating temperature (I didn't drive it though) on a maybe 90 degree day.

Thoughts?

[aspen]

Ok, a few gained insights:
1) I've got a very, very small coolant leak in the throttle body heater pipe.
2) Radiator cap doesn't seem to hold pressure

And on the electrical side, there's a few things that might be strange? I would be super-appreciative if one of you guys could confirm some resistances for me:

Temp connector ground to battery negative: 101 ohms (seems a bit high... Odd though that this connects to the E2 on the ECU though. Maybe I could just fork this so that a part of it grounded to the block as well or directly to the battery)
ECU connector to battery ground: Infinity (this seems good)
Gauge to Battery ~40? (definitely nonzero, I forgot to write this down)
Connector ground to gauge: 40 ohms
Connector ground to ECU: Infinity


I'm most curious about what the connector/battery ground to gauge is. I believe it should be nonzero as the gauge needle will have some passthrough, I'm just curious what it is.

As far as the connector ground to the battery ground, I have yet to check the grounds on the back of the engine, but I'm pretty certain they are good (mostly because I forgot them the first time I tried to turn the car on).

Thanks!