Car wont start unless door is open

What I think might be happening, is that either you are unknowingly wiggling/ jiggling a harness enough that it makes or breaks a bad connection, or there is simply something intermittent. It might just be in the ignition switch.

You need to get serious here. Figure a way to connect your meter to the ouputs of the switch so you can SEE them, or do it with lights. See if the light goes out or dim when the problem is at hand right there at the switch. if that is OK, move to the engine side of the bulkhead connector.