Slant 6 wont idle after warm

Idle/low speed circuit is clogged or blocked.
It runs as long as the choke is partially closed because it is forced to pull fuel through the booster. Choke opens, and now it can only pull fuel from below the throttle plate.
The fact that when your car died on the freeway, you couldn't get it to drive off tells me the transfer slot is dry.
That is controlled by the idle/low speed circuit
That is most likely.
If your engine is later model and has an EGR valve, it could be hung open causing an internal vacuum leak