Slant six Holley 2280 stalls when stopping

I was posting to "Slant six 1920 stall" so to avoid confusion as I am using the 2280 I am creating a new thread.
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(Sorry for long thread.)
At issue, slant six 225 rebuilt about 1k miles ago if that, I don't drive it far nor often. Car will not idle well, if I try to get it to 650 rpm it will run a bit then choke, dying. Hitting throttle will start the whole process over again.

It will run at 1200 rpm for long times, hasn't died at that rpm but is a bit rough idling.
if I hit the brakes hard when coming to a stop the engine seems to want to die also idle speed drops faster the harder I hit the brake.

Thanks to AJ and Rusty and DogDish, Killer6, Bewy, pishta, I have done many of the things suggested.

Here is info on car and the work done.
Holley 2280 rebuilt at time of rebuild about 8 years ago.

It has an Oregon Cam #819, intake and exhaust clearance is listed at .012. Valves adjusted there.

The fuel tank has no vent in the system. I traced it from the fuel filler and there is a small 1/8" or so pipe that runs "torturously" from the filler down the neck to the tank, when I look underneath, the pipe is hanging in the breeze no connection.

It has no PS so no brake booster.

It is a manual brake system.

It has an electronic distributor.

Car will diesel a bit when shutting off when warm.

Timing is set to 5BTDC right now, changing does not affect the stall, adv nor retard.

Replaced plugs last month. which were somewhat fuel fouled.

I installed a new electric choke.

Adjusted the floats to 9/32 and cleaned the bowl out as there was a bit of crap there. Took out the idle screws and blew out the idle circuits and others.

Replaced the funky PCV hose as it was collapsing when running. Does not collapse now.

Plugged off the carb vacuums ports including small ones on front.

I tried to check fuel pressure with my pressure/vacuum gauge. Tee'd into the fuel line with the tee supplied with my gauge but it is like an 1/8" tee and my fuel line is bigger. Tried to clamp it shut be it leaked and the plastic tee broke.

I also sprayed some starter fluid at the throttle bushing area and it would speed up leading me to believe the Holley is worn. (perhaps the gasket?)

Checked valve springs and push rods. All seem fine.

Not Done.
Unable to do pressure test to verify 4.5 psi, looking for a brass tee that will work, or does someone have another way to check?