Idle Surge And Overheating

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So i have a b20z2 swapped into a 2000 civic with a ysk-2 trans I'm having a overheating problem where after it heats up to operating temp it loses power and gets too hot. i have a aftermarket rad (fuidine brand). I'm wondering what could cause this it has a new thermostat and the water pump is good. however i do not have a coolant overflow so I'm thinking that might be part of my problem and my rad cap is old and the rubber is cracked and i can see it leaks a little bit. I also do not know if the distributor is in the right angle or if its been adjusted. curranty its in the middle of the slider. i know that if its not adjusted right that could cause it to overheat too.

I also have a idle surge problem i have already replaced the map sensor and the throttle position sensor is good as well. it surges when its warm and cold and more fluctuation when its in the too hot state. I've seen that the surge could be caused by dirty injectors so I'm thinking that's it too.

I've attached a photo of my engine bay to give you a better idea of my setup.


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The overheating and surge could both be a symptom of air pockets in your cooling system

If you have janky parts in there then replace them, but before you start throwing money at it, make sure the simple stuff is covered
New clean plugs
Good wires
Distributor cap and rotor in good shape
Distributor set correctly
No air in the coolant
A complete coolant system (even if you have a bottle acting as the overflow, it is better than not having anything)

From there once the temps are in control if you are still getting a surge you can maybe start looking at electrical... Signal, ground, etc...

But to start get a new cap for the radiator
Get some sort of overflow in place
Check plugs/wires
Make sure the timing and distributor are right and in good condition
That's what I was thinking for the first steps. I did bleed the system when I put the thermostat in and it was doing it before and after it was bled. I also just added coolant for what came out. Could it possibly be that I need all new coolant?
Running rough once hot can be an indication of a bad head gasket. Napa has some fancy block tester solution that reacts with exhaust gasses if present in the coolant. It doesn't always work depending on where the gasket has failed, but its a cheap and easy test.

A good vacuum bleeder is an awesome tool to have as well.