Electrical power has _nothing_ to do with the engine shutoff .

The yellow pipes are the only ones that should be connected to the yellow one way check valve .

Sounds like you're getting there .

The 5-way connectors are still available, as far as I know. A few places offer them, including Peach. $25-$30.
Part number 1268050022

Then you explain why pushing a self-contained electrical button causes prolonged run-on.
And before you say the seat back locks, the blue line is and was capped before the vacuum gets to the seats, and hasn't changed since, and now the car shuts off. (Heck, I might even plug the seats back in to see how flaky they are.)

By the way, who said anything about pulling other lines into the yellow check valve?

The door jamb switch is a combination , not just electrical .

I can only reply to what you've said .

Don't make things more difficult than they are already .

Update: I played the game of plugging lines individually, and got the car to stop with the green/yellow (ACC) line blocked. I reconnected it and the car ran on, disconnected the line and it stopped.

I have a replacement coupe door jamb switch in my possession and I swear to you there is no vacuum connection to it.

Could an ACC switchover valve leak somehow increase when the door switch is pressed?

This is still all just 90% certainty, since the car healed itself again before I could actually fix it properly.

Wow ~

How much hair do you have left ? .

I wish I was there to see what's what .

I just finished chasing down all the leaks and things in my Sedan, the engine stops almost before they key is finished moving, it's eerie .

I can't wait to do the same to my Coupe......

You'd think it should be as easy as swapping out a switchover valve.

I replaced switchover valves number 1 2 and 3 a few years ago and I thought that fixed it, but I guess not.

With the EC button pressed, the wheel turned to MAX cold and fan on high, I wouldn't expect the defrost vents to be blowing full blast, but they are. I swapped in the old 1 2 and 3 switchover valves and it still does the same thing. Is it possible the ACC unit itself is the culprit?

The center vent vac pod is bad- very common problem. I usually remove the glove box and instrument cluster to gain access to the center vent boot. I remove the rod from the vent flap so it remains open. I can then control air flow to the center vents with each vent valve.

That sucks. I changed it out when I removed the dash about a decade ago. The car should still shut down if the switchover valve switches, though shouldn't it?