Hot start problem, Checking opinions before I buy a new battery Options

[Highland]

My car starts easily when cold, but hot it has been a struggle. I put a variable resistor on the CHT as an experiment without success. Engine's not even catching.

Plugs look good, 123 distributor, blue coil, valves adjusted, runs fantastic once started.

I am using a 2 year old motorcycle AGM battery(which has been working prior to 123 distributor install). Open voltage measures at 12.6V.

I stuck a lead on the coil while cranking and voltage drops to around 10V and will bounce down to 0 occasionally if I crank for more than a few seconds. With ignition only the coil is at about 12.3V.

The blue coil is an NOS coil that I had. It's probably over 30 years old but resistance is good when cold. I did not think to measure the resistance hot, but would it make a difference? Does the insulation breakdown over time even if resistance is good?

Thinking my little battery doesn't have enough power to crank and fire the coil. Any opinions? Cranking is strong.

[Highland]

I know I'm getting fuel, so I've been focusing on the ignition. Tried swapping to a "cool" coil after a run with the same results. Also cleaned up the ignition wire contacts hoping that would make a difference (at which point I planned to buy a new set of wires).

Should have done this first, but I unplugged the FI trigger points and cranked the motor to look for spark on an exposed spark plug (it did spark). The motor tried to start with no fuel. I tried starting the car with open throttle (set in place prior to running pump) and was able to get the car started. On a cold start I just turn the key and the car starts every time with closed throttle.

So I'm way too rich on hot start. I don't understand what controls pulse length during starting. Aside from the CHT (I did not add a resistor), are there any other controls? Does the ECU see the MPS at full throttle during starting? As long as the throttle is in a fixed position prior to the pump starting, does the TPS play a factor? Does ECU idle knob effect starting pulse length?

My cold start injector is not hooked up and injectors were rebuilt by Mr. Injector so I'd be surprised if all 4 were leaking, but I guess it's possible. The plugs look good with that brownish white electrode color so I think my mixture is okay while running.

So what knobs can I turn to lean out hot start?